RB751U-2Hn frequent (daily) reboots

Then I hope there are still changes compared to 5.15RC1.
I got one in the field, 100% CPU, can’t ssh / winbox to it (doesn’t accept the password).
I had it rebooted by a local user, comes up at immediatelly 100%, still unable to login. I go onsite tonight.
It was running 5.15rc1 for less then a week. I get so bored of that RB751U-2HnD thing!