Dead Pc, dead in the water
I would just like to point out that PCs are not designed to be run submerged.
On the serious side:
You indicated in a previous post that the power off problem has happened before and that the PC powered back on after:
You didn't share those same facts here. Don't eliminate the possibility that the power supply itself is the cause of the problem. If there was a loose connection in the power supply that caused the original power off problems and after the latest bump that loose connection is now an open, you will not find the problem by doing any of the above suggestions.
I would attempt to borrow or buy a power supply and replace the current one to eliminate that possibility.