From TechnoDocs
The power receptacle is located at the back of the box.
It will have the power cable running into it.
To check the fuses:
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.