Someone dropped off a broken computer about 15 days ago. The only symptoms
were that it didn't boot-BIOS/no-cpu-fan but greem-led-on-mobo was on.

I swapped out the PSU, etc and end result was that the CPU fan was toast
(didn't spin on a 3-wire header) and so was a gfx card (tried to POST on the
VGA of a working box - PCIe card)

Got it working and sent it back - put in a new fan) - unfortunately today,
the box is dead again. This time: the fan's fine, but the mobo cpu-fan won't
spin at all (no boot-bios) no matter what i do (swapped the PSU, ram, etc).
Green mobo-led is on (same as before).

I tested the cpu-fan (4-wire) on a 3-wire header and the fan spun up but
that doesn't exclude the possibility of a the ctrl line on the fan being
damaged.

1. What should I do?
2. Would it be reasonably honest to tell him to buy a new pc? I'll have to
junk the PSU/mobo/cpu/ and possibly ram too.
3. How do i exclude power issues (bad smps, wall power)? How likely is this
to be the cause of his misfortune?

(it's not a cmos issue, new battery, flushed cmos etc)