Radio froze, 2nd day no menu/audio 3rd day all black!! NO DRIVE!

So I recently replaced modules in my 2001 HV battery, and all was more or less good, a few hybrid system warnings (still one saggy module at bank 13), but no more high-revving freeway failures like I was having before.
All was fine for a week or so, then 3 days ago I drove it and the volume control on FM radio 'froze' and would not change when the knob was turned, nor could I shut it off...after a few attempts I got it to say 'audio off' and left it off. Tried to use it next day and it would not respond but car still ran and drove fine. Still no menu or audio.
YESTERDAY, I checked the fuses at left end of dash to see if it was a blown radio fuse, nope. swapped horn relay for the one above in driver side fuse/relay box under hood (swapped back today), passenger side relay box the ABS relay lid popped off in my hand.
TODAY: got in the car, ALL BLACK on the dash! NO instrument cluster lights (dim 'door open' light only) NO energy monitor back light either! WEIRDLY, the ICE starts and runs! BUT can't shift out of park, brake pedal to floor, no steering!
DID I CAUSE THIS SOMEHOW?? Checked relevant fuses and visually inspected relay contacts, none blown, none fried. I'm assuming all the large 'visual' type fuses are obvious when they're blown open? I also tried today unplugging/plugging connectors at the passenger side ECU and ones behind glove box, as well as a couple near dash fuse/relay panel.

 

I've checked it, my meter showed 12.1 volts so maybe that's it, but ........if you read my post, the ICE runs..so I ran it, then metered it after 1 minute of running then shut off, aux battery rose to 12.6 volts.
I'm putting it on a trickle charger overnight in case you're correct. I doubt it though, because cabin heater fan doesn't work, blinkers don't work (hazards do), brakes steering and park release are dead, park button is locked.
I'm thinking cabin ECU or bad/fried connection behind the radio cluster or maybe under the metal plate on passenger front floor (had an intermittent P0420 for a couple years prior and was going to check connections in the same spot for that but never did)?
If i figure it out I'll post a follow up since I've not seen a single post with the same symptoms, or at least I'm too old, blind and impatient to find it!

P.S. this is my FOURTH time pulling out the traction (HV) battery, replacing modules, and reinstalling. Owned it for about 4 years....

 

The trickle charger is already showing steady green and staying green. The hybrid system is obviously charging the aux battery so good news there. The theft alarm/horn also work! I had the trunk switch cheated while I cleaned up the ground terminal at the body just now! That woke me up....

 

Okay, I know it's not the aux battery it has plenty of voltage (the prius battery isn't supposed to read nearly 14 volts) and I bought it NEW less than 2 years ago, it's still under warranty. ICE starts and runs, half the electrical still works as previously posted. I checked and cleaned/retorqued 5 body grounds as well. Sorry, you dislike my maintainer or me calling it a trickle charger but it seems all 4 of the batteries I've used it on like it just fine, including the 2 yr. old prius' battery.

I obtained a wiring diagram manual (nearly 2000 pages) and after reading through it and searching for relevant issues/sections ( think i got my answers by page 1300 something) I think it's either cabin ECU (left end of dash behind fuse/relay block) or hopefully the gateway ECU mounted on top of the tape deck. When I checked the diodes on the GATEWAY ECU, 3 of 4 were blown open (OOPS i was wrong, not blown they test fine). Maybe a short someplace, maybe the other ECU or display ECU also. Funny though, the manual mentions how that little cigarette-pack sized unit passes and translates signals between DISPLAY, ECUs, and RADIO/NAV option, etc.
Get this: dealer price is over $800 'on sale' but I scored a used one for $4.00 plus shipping and tax!

 

No faults at all, not even relating to the HV battery. As posted initially, that part was all fixed, then radio crapped out 2 weeks or more after I was showing 40+mpg.
Good call, after reading manual I also scanned the OBD with my Torque Pro and Pantech dongle (sorry no techscream) and no codes at all. Of course I do think presently there is a communication issue because It should have given me a code when I turned it on with Gateway ECU unplugged, and nothing.

 

I have very pointy probes and I poke them hard and twist. Usually that works even when the first probe doesn't but YOU WERE RIGHT, the D1 and D2 are just larger and had thicker coating on terminals. So NO bad diodes? I even checked the ones on the opposite side. Not all of them go directly to a pin anyway. Thanks, good call on re-testing diodes...but kind of just a time-killer because if an IC is blown internally that's a bit harder to test for without details of chip pin-outs/functions. Maybe even needs powered up to test certain stuff...I don't want to repair a 9 dollar board when dozens are available.

 

Yes, I've been checking connectors as I go along, and I've found in the manual which wires to check if gateway doesn't instantly fix it. I'm gambling it won't fry immediately on power up.
As far as torque pro vs. Techstream, yeah I know there's no comparison but I can't afford techstream.
I did throw away my cheap OBD bluetooth interface when I bought a Panlong unit (thanks again priuschat!) and now it gives me main codes without fail, but I can't see sub-codes ever, you're right.
I AM POOR!

 

Sam:
Okay just to satisfy us both, and to prevent more posters from jumping on the 'AUX battery' dogpile, I removed the prius' battery yesterday and drove it up to the store I purchased it from (the big O) and had them test it. It's 7 months past its 3-year warranty. The day I bought it my meter read it as 12.6 volts. It still reads that after a top-up charge, but certainly not after an evening of drain from the ECU, and also my insurance dongle. About 12.3 volts. I had them test my old nasty truck's battery '87 GMC, bought battery in '03 also past 100-month warranty) because it won't fire the starter sometimes. IT WAS BAD! No shock there!

I went back to my buds at Costco, and traded my core in for a new top-post battery with nearly 13 volts showing on my meter after charging it on the way home with my alternator. Yes, my truck has an actual ALTERNATOR! To further satisfy our yearning need to know, I hooked up the brand new battery to the prius, STILL BLACK DASH.

The 'nearly 14 volts' I was referring to, if you read carefully is not referring to any prius battery but what I remembered my truck's battery reading when IT was new back in 2003. My point was, to be crystal clear, that no Prius battery I know of OR CAN AFFORD TO BUY reads over 13 volts. EVER. Does the OPTIMA battery crank out 14?? If so it's probably why every one of us who CAN afford one opts for the Optima!

I'm sick of dealing with my old Primus so I'm gonna relax, spend time with my son, and forget about even trying to fix it for at least today. Thanks all for your help, thanks Sam for you first and fast reply to remind to check that AUX FIRST! Which I did! You believe me now, right??

 

Not EVERYTHING. Just half of everything. I've been checking voltages past couple days and I'm definitely missing voltage at the driver side Junction/fuse/link box, depriving cabin JB of juice. But only on some things. Mostly the things I need to drive the vehicle!
Horn, Hazard, Door locks, Dome, Stop, Tail all WORKING.
Wiper, Radio, Cig, ECU-IG, Headlights, Heater fan, AC, DEF, Park solenoid, Combo meter (instrument cluster display), MID (energy monitor screen), ALL DEAD! NO VOLTAGE.

 

UPDATE: After checking with the dealer to confirm, it turns out my car has been missing the fuse AM1 in the dash driver side fuse box SINCE I BOUGHT THE CAR! So, apparently it was bypassed by someone before I ever got it, and now that circuit is open. So I have to figure out where the wires for that circuit are now, and install an in-line fuse (I'm assuming the fuse terminals in the box are likely fried, or broken which caused it to be rewired at some point.
If anyone reading this OWNS a 2001 I guess they can confirm that they see the same symptoms when they pull their AM1 fuse, or refute the dealer and confirm you don't have that fuse in your box either and it runs just fine??
THIS, I find out AFTER ruining my 100A DC/DC fusible on purpose (don't ask) and removing the engine driver side fuse/relay/link box. Which I had to remove anyway to replace that fuse link.

 

UPDATE, PARTLY FIXED!
WAS I PRANKED? It was just before April 1 this happened, and I did walk away from my car for a couple hours but maybe it's me, and I pranked myself...I've never failed to put a good fuse back or replace a bad one in 50 years of fixing cars but maybe??
After thinking about what to do, I bought a box of fuses, inserted a 5A into my AM1 slot, AND THE COMBO METER AND MFD LIT UP ON ACCESSORY AND ON......for a few minutes of testing. BUT: I had the radio disconnected!
My gut told me to LEAVE IT unplugged, but wanted tunes so I plugged it back in but pretty sure plugged in wrong because I think i plugged the male (identical shape but not number or color of wires) plug that feeds the CD pigtail directly into the passenger connector INSTEAD of the 'Y' cable male from that pigtail! When I turned the key back on, in seconds I(?) KILLED THE FOLLOWING: MFD (touch screen), Door locks with key off (but they work with wireless fob!), clock, radio hasn't worked since 2 days before combo meter/display went black. The car now runs and drives still, albeit without any of the listed. Checked cabin fuses AGAIN, bought a used radio for $45 because I want tunes w/out earbuds plugged into my phone, I'm SUCH an idiot!
NOPE, still no radio but maybe if I find the blown fuse, link or circuit it will work.....who knows?

According to a poster who went through a LOT of hell trying to install an afermarket radio, he says my MFD (touch screen) won't run with radio 'left connector' (driver's side?) unplugged. Mine worked with NO connectors in radio/tape deck unit! He may be referring to the connectors on the switch interface board that has all the audio/menu/info/volume, etc. connector? Mine was connected when all the stuff worked and lit up before I had my bright idea to plug in radio/tape to make the audio work!