I have had 2 of these amps now that both had the exact same symptoms. I bought a second hand one and after several gigs it started to give a moment of speaker rattle and buzz then cutoff completely. After 10 or fifteen seconds it would come back on. I tell you, in the middle of a busy gig it felt like it was off for a lifetime! Being unreliable, I replaced it with a brand new unit. The same thing started happening in the middle of a gig. So it had to go back.
It’s a real shame, as for the price point, the amp is of good build, is very light, powerful and loud. The toneprint feature is a bit gimmicky and has little practical value.