
Bummer.
First things I'd do, in order of "cheapness":
1. Let the amp cool down and try again later, in case it's thermal overload of some sort.
2. Check or replace the fuse. You'll have to buy or borrow a multimeter to check the fuse properly, but a meter is good to have anyway. In the future you'll want to have a few spare fuses as well, especially when gigging.
3. Start swapping tubes. Even if they're lit, doesn't
always mean something inside didn't peeter out. You don't have to buy a whole set of tubes mind you, just one of each kind and swap it out one at time, powering the unit down between swaps of course.
4. If none of this works, time to contact either Peavey or a professional, depending on if the unit is still under warranty.
Good luck.