If they supposedly 'fixed' the problem while it was under warranty and it has the same problem, they are probably liable for the bill.

However, if it's only a 'similar' problem and is a different component or another area of the wiring harness, you will get stuck with it.

Lastly. Short circuits usually produce blown fuses. If it's shutting down components, then it sounds like a bad controller box of some sort. It is too bad you didn't keep the receipt, I could probably narrow it down better.

Good luck!