from the sounds of it youre on your own when it comes to getting this fixed.
if you have any electronics knowledge this will be easier. if not a few google searchs i think youll be alright.
start by opening the unit, im sure there are some phillip screws holding the out case together.
then try to find the PCB and see if there are any obvious signs of dmg, burning , scorching, corrosion. things like that.
also check to see if there is a fuse that may have blown.
having a multimeter will DEFINITELY help with troubleshooting this. also post some pictures up on here to help with narrowing down the problem!
good luck!