First thing I always do at a new gig, is check each outlet with my tester, that I plug in. Grounded correctly, hot and neutral wired correctly? I had a gig last week where I needed 2 outlets, one was good, the other was hot/neutral reversed. Guess what I did? I killed the breaker, and pulled the outlet, and swapped wires.
What some place never know...geesh
Sorry to hear of your bump in the road, sure hope you get your amps back and running again. Warranty?