If the fuse is blown, the amp will not turn on and a new fuse need to be installed.
Insert any tool with a small, flat end (such as a spudger, flathead screwdriver or plastic opening tool) into the groove in the bottom of the power input and wedge the plastic slot out from the amp.
There will be two compartments (one enclosed, one exposed) each containing a fuse. The exposed fuse is the active fuse and the enclosed one is a spare.
Remove the blown exposed fuse and replace it with the enclosed fuse. If there is not an extra enclosed fuse, a new fuse must be ordered and inserted into the exposed slot.