The power receptacle is located at the back of the box:
It will have the power cable running into it.
To check the fuses:
Lock out power
On receptacles made after 2007, there are two tabs on the side. Press them inwards to extract the fuse holder.
On some older units, you may need to use a small screwdriver at the bottom of the fuse holder to pop it out.
Use a Multimeter to verify the fuses. Sometimes fuses that look good are burned.
Multimeter: This is a picture of a multimeter. Yours may look different, but the important symbols should be the same.