Can a kid fooling with the hardware profile really kill the CPU or MB?
No, but other things could cause it - like a static shock to a card, a dead card shorting the board, O/C attempts etc.
The problem now is to determine if it is the;
a - Power Supply (faulty atx lead)
b - Cooked CPU (heat or short or overvoltage mod by user)
c - Mainboard (dead circuit on board)
Of the 3, the CPU or mobo would be most likely, but not necesarily.
The UWAVE board is Amptron if I remember right, and is not great in performance or expansion
The PSU in the unit should be upgraded to 300w if you upgrade the cpu/mobo
Since the motherboard, ram and 1.2ghz cpu are from an older model line, and upgrade will most likely require replacement of all 3 - maybe even the psu too - you will be best to have it tested by a shop at this stage (I could test but you are pretty far from Van)
Make sure that it is out of warranty - they may have got 3years at the time and it sounds like 2 years old