I recently "inherited" a used Fender Rumble 100 v3. Nothing happened when I flipped on the power switch. No light, sound...nothing. I tried different outlets and different power cables. Still got nothing. My next step is to check the fuse. However, I cannot locate it anywhere. I think it's internal or inside a case I don't recognize. Does anyone out there have any knowledge to share about the location/how-to replace the fuse? Thanks!