dash lights on while no fob in or near car!

I'm no stranger with troubleshooting/fixing Gen II Priuses but this one baffles me.
My grandson's 2005 prius had a dead 12 volt battery. I tried to charge it but finally determined it would not take a charge so the 12v battery must be open or internally shorted.
For the time being, I hooked a high capacity deep discharge 12V AGM battery. Connected + to the cluster w/the fuses and the brake controller wiring, the other to chassis ground. Wiring heavier than the normal 12 Volt battery wiring.

As soon as the battery is fully connected all dash lights come on. The combination meter comes on, although with blinking fuel pip(s) and no status indication on the shift display, obviously no Ready light. Nothing else works.

insert the fob and the "no key" light goes out, the check engine light extinguishes, an an orange indication in the start button. No start action, and the other warning lights remain on. Windows work. Hybrid battery voltage is 218 volts. Green flashing light in the "Park" button.

Push the start button again (maybe several times) but the lights remain and the fob remains locked in the slot., so I cannot shut the thing down unless I disconnect the 12V battery.

I am totally stumped. No idea whatsoever......Ruud

 

Thanks for responding so soon. But your assumption that the + terminal of the battery is connected to the "jump" terminal is incorrect, that way I would miss all the other required connections (fuses, brake controller).. from my original post:
"........I Connected + to the cluster with the fuses and the brake controller wiring, the other to chassis ground. Wiring heavier than the normal 12 Volt battery wiring......"

 

Your "lightbulb" interpretation is correct. The problem is that the car is powering up when it shouldn't. No fob anywhere near the car, and the dash warning lights come on. I'm beginning to suspect that I have a "fried" relay somewhere that is stuck in the "on" position, acting as if the fob is in the ignition slot. will examine the wiring diagram......RH

 

This one is for the Gen II Prius experts: It is a follow-up on my previous post (see above)

My grandson’s 2005 Prius with 214K miles on it, has sat in his family’s parking lot for about 7 months. When I tried to get it running, all sorts of weird stuff happened, none consistently. I finally charged the HV battery with a Prolong charger, and replaced the 12V battery, and finally got it running albeit occasionally with no combination meter . When the CM is out, I have to hold the Power button for 3 seconds to start it or shut it down !!

It has been throwing error codes left and right, Mostly U and D category, none clearly indicating a specific problem area. When I get it going (warning lights on), it runs OK, but then after about 2 to 5 miles, the battery suddenly cuts out and it is just the ICE running the car. Then the ICE is running at high RPM( 3600 – 3800 RPM), slow acceleration, low constant speed etc. The MFD shows no power coming into, or going out of the traction battery, verified by a Scangauge tool which shows 0 (Hybrid) battery amps, but good Hybrid battery voltage (between 229 and 235V). When this happens, it is normally only accompanied by a code P0000. But then when you shut the system down and power it back up, all will be well again. Maybe for the entire trip, or just maybe for the next mile or so.

The combination meter sometimes works, sometimes not.

Anybody have any ideas ??

 

For the time being, I'm ignoring the combination meter. Can always fix that later, although I hate tearing the dash apart.
Techstream says I have codes P014 and P023. Those are two weak battery blocks, and I know how to fix that. Actually the car seems to run fine with those two DTCs set. It is the dropping out of the battery relay (audible) at some point during the drive. Techstream also comes up with DTC P3000 which comes from the battery ECU. Subcode is 123. I need to find out what is causing this.......Ruud