N72 & One Shot Power problem

[dday]

Really hope someone can help.

I've just finished building an N72 to be used with a prebuilt One Shot chassis. Everything appeared to be working fine on the first test: powering up and amplifying well. After a few minutes the power adapter starting getting really hot and giving off a terrible smell. Subsequent power ups lasted shorter amounts of time before the power LED turned off. Now the unit rarely powers up at all (for a second or two if it does) even with the N72 power molex disconnected from the Power / DI board.

I've tried a different power adapter which is fried completely now, different sockets etc.

Please help, I'm pulling my hair out!