I use a Sunn Concert bass head that stopped working. Other than some scratchy pots it worked wonderfully before I just had to record a bass line in the wee hours. I took a chance and plugged the line-out direct to my board but didn't connect anything to the speaker outs to bear the load. The recording came off without a hitch but the next time I plugged the amp in I got no sound. I would add that the lighted switch also didn't come on, but it never did even when it was working.
Is it just a fuse? And can I fix that myself? Despite playing for 22 years I've never taken an amp apart.