CPU or board I would imagine, or both.
In desktops when the power supply goes from a large surge like that it can leak onto the board which kills the board and sometimes the CPU.
Basically the unit is junk and even if you replace the board and cpu there is no way of telling in advance if the ram or drive are still good. You might spend a lot of time replacing the board and cpu to find out the inverter and hard drive were damaged by power surge too.
Try pulling the battery and ac off and hold down the power button for 25 seconds or so to clear any residual charge and see if it fires up. If not I probably wouldn't bother with it.