I broke a good car, I'm in trouble, help me

Another telltale thing, short of reading the P0A0D code, is that the presence of that code locks out going from OFF to READY at all, as I believed in #8 and jzchen confirmed in #18. That doesn't sound like the behavior being described here.

 

Replacing the head gasket involves a lot of manipulating of wires and the fuel rail is removed. The main fuse for the ignition and fuel is ok? Fuel, ignition, and air, engine should run.

 

Good to hear!

May we ask which fuse?

 

Yeah, I'm really curious which fuse as well. There is one inside the orange disconnect assembly, if I remember correctly, but you'd have to have a pretty good short to burn that puppy! You would be hard pressed not to have heard a whallop of a bang that would probably cause a person to release some bodily (ahem) "stuff" as a result! This makes me think that the OP must be talking about a small 12V control fuse someplace. You could burn that out and barely hear the "tick" of the arc.

OP: There is no starter, per se, in a Prius. The traction motor functions as the starter for the IC. This is important to understand becasue without the high voltage battery, you will not be able to start the car. Yes, there is a 12V battery, but that only powers relays and other accessories. Unlike a traditional ICE vehicle which uses that 12V battery to power a starter, the Prius is a different beast.

If you do drain your HV battery, you don't have a lot of options. One is to take the HV battery out and find someone with a HV charger (or tow the car to that person). Dealerships should have the charger we are talking about. The second is to charge each block individually, but you DEFINITELY need to know what you are doing if you go down this route (there are lethal voltages inside the battery). Another would be to get a charger such as a Prolong charger, but that requires a wiring harness, the charger, etc, etc. It isn't a bad longterm solution to improve your battery life, but for a one-off, it would probably not be the way to go. Oh, and this also involves installation which you should be careful doing (again, lethal voltages). Absolutely DO NOT hook up a 12V battery to your high voltage battery! That can definitely kill you or maim you with sulfuric acid being thrown around in an explosive fashion.