McIntosh Tube Amp will not come on.

They picked up the phone on the second ring when I needed tech support.  They were super helpful.    Definitely call them 

I've had a MA352 for three years without any issues.  I have called McIntosh support for questions and they were very helpful and responsive.  You'll speak with a tech not a call center front person.

Same. Mcintosh picked up every call unlike nearly almost every other manufacturer I called.

One more thought; try doing a factory reset.  You'll lose custom settings but that may do the trick.

I had a similar problem, I held the power button down for too long which caused the tubes to keep glowing orange.
I had a technician at my home in Brooklyn within two days to take care of it.
Call MacIntosh!