It's not under warrenty, he bought it used about a year ago from a member this site. We'll check the wires and get back.

In the meantime, if the power supply or output stage is meessed up, is it just as well to find another amp, or would it be feasible to fix.

 

It's a good enough amp that it would be worth spending $20 or so to have it checked out if the wiring is not the issue.....

 

Ok, so we looked at it tonight. Measured voltage at the amp terminals was 12.6V. Measured final resistance was 1.0 to 1.1 Ohms. We disconnected the positive cable from the amp, and put two 20A fuses in (Since we didn't have 2 40's) When the power supply was re-connected, all was good, no fuse fault like as before. However as soon as we turned the HU on, two of the fuses popped.

 

Your friend's amp is broken and will need to be repaired. If it didn't burn anything too badly, around $100 - $200 should fix it.

Good luck!