McIntosh Tube Amp will not come on.

Some pretty ghoulish stories of their newer equipment not working with remote, slow repair service.

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.