I'm not a repair person and when it comes to power supplies dying my solution is to replace the power supply so that's the only thing I can reasonably suggest.
You could try looking on eBay for another one. But actual repair of the one you have, sorry I have no idea how to do that. Maybe someone else here might have an idea.
I am assuming that you wish to repair rather than replace. But if replacing is ok, I can point you to a good vendor.