amp de-powering soon after power-on

For all your electronics wizards on this forum, what would cause my Bryston 3BST to turn itself off, several seconds after manual turn on? It is doing it consistently.

I assume this is a protective maneuver. Is it a short? Fuse??

I've checked the power cord; changed it to a different power strip; checked all other connections. Since I am a mere consumer, I don't know what else to do.

The amp was working fine last week. It's in my office system, which was off over the 3-day weekend. I know I can send it to the company, but am wondering if I can fix it on my own. Thanks for your help.