???? READY LIGHT INOP

i think there are fuses near the hybrid battery, 12v battery, drivers footwell, under the hood, maybe a quick scan of the service manual at techinfo.toyota.com

 

Have you reset the error codes? The car won't necessarily clear them just because you fixed a problem. You need to clear them and hope that they don't return on the next restart.

How certain are you that your new battery is any good? Replacing one bad battery with another would be an easy way to get your current result.

 

Seems drastic to buy a new car instead of asking the dealership for help. Hopefully resetting the code fixes it.

 

Obviously, no one just pops apart an HV battery, snaps off a terminal, slaps it all back together and then tries to drive it. What was the purpose of even touching the HV battery? Something had to trigger this entire episode? Fault codes, running funny, etc?

How about starting from the beginning, so we can have a better idea of what you have going on? I'm sure we can help.

 

nothing but crickets???? Guess a new car is in the books!!

 

This right here is why we can’t have nice things. I would bet it blew the fuse in the orange safety disconnect. I’m pretty sure there is one, yes? You can’t expect to short out the HV battery and not expect something bad to happen.

 

From my experience in rebuilding wrecked Aquas, during a critical failure (Such as crashing into a brick wall, accidentally dropping the engine out of the engine bay while running it on a car lift, or, in this case, breaking off a bunch of tabs in the traction battery, slapping it back together, driving it, and something shorting, causing a failure), the car will enter something of a safety lockdown mode.
In one example I have, a head-on crash, the cables connecting the inverter to the ECU where severed, and needed replacement. During this time, the car displayed a large number of errors.
Simply replacing all the damaged cables and components wasn't enough to get the car running again, as the errors persisted. It was only after clearing all the error codes that the car was willing to exit this "Safe mode" and attempt to start up the high voltage system again.
In your case, I'd swap out the traction battery with a known working unit (which it appears you've already done), then check every fuse in the car you can find, then try resetting any and all error codes. Once the codes have been reset, look to see if any come back, as this could indicate an unresolved fault. Repeat until all faults are cleared.
If you've done this and the car's still not starting, either you have not fixed everything, or you have, and the ECU is refusing to allow operation regardless.
If it's the latter, then a toyota service centre may be able to do a hard reset on the ECU, for a price.
I'd suspect that, in this case, there may be damage to the inverter, as an emergency HV shutoff, while driving, due to shorts in the traction battery isn't exactly something the car is specced to remain functional through.
Come to a safe stop, yes, but if the car's detected that a fault this severe has occurred, chances are it's decided to call it a night and will refuse to drive until someone the car trusts has told it that everything's good.
Just because the fault condition no longer persists doesn't mean it'll be willing to go out and drive again, as doing so could easily result in a fatality.
"and it started arcing to the copper plate while driving it and shut off"
I'm curious as to precisely how you know this is what was happening while driving.
Arcing sounds coming from the back of your car in the instant before it entered crash mode doesn't mean it was specifically the area you had previously worked on, it could have been a number of things, such as a contactor under high load trying to open due to another detected fault unrelated to the snapped battery tab.