Hi,
I'd be careful opening up a power supply. There are many stickers and
warnings on the power supply that opening the power supply and doing
anything may result in an electrical shock.
There are many capacitors inside the power supply and they can have
electricity stored in them that can give you a pretty good jolt.
There aren't any user servicable parts inside a power supply either, so it'd
be tough to fix it.
I'd just see if you have another power supply or just buy a new power supply
and put it in. They're relatively cheap anyways.