The bad electrolytic capacitors, if you have them, look like this:
If they're flat on top, then they're probably fine. If they're bulging or split open and leaking, then you'll need a new motherboard.
Good hint on the capacitors, although I seem to recall that problem was mostly confined to MSI mobos, and not ASUS.
I might be mistaken, but I think the majority of bad capacitors ended up with MSI and they actually settled out of court in a class action suit brought against them.
I lost a MB to bad capacitors, and the machine will not turn on without the caps. His machine turns on, so I don't think that's what we have here.
Also, the caps make a strong ozone smell when they fail. I thought my house was on fire. It's very noticable.
When I looked at the MB, the caps all had what looked like chalk coming out the top.
Also, the capacitor problem goes back a couple of years, so if he has a MB with bad caps, it would have already failed.