Sounds like it could be a hw issue.
Had similar in the past with my Ultimo4K.
Try turning the power switch off (on the box), then turn it on again, but press it fairly hard into the on position.
It might take a few attempts but eventually you should get it in the right place.
If it is that and once you do get it in the right place, never touch the switch again, just pull the power lead out or pull the plug out the wall in future (mine has been fine for about 4 years now doing that).