Quoted from MysteryEncoder:PCB overheated, common problem with the first generation of them. Contact arcade1up they'll give you some fuss about being out of warranty and still send you a replacement PCB. I highly recommend keeping the PCB out of the metal case as that thing just adds to the problem at the moment the way it was designed.
https://arcade1up.freshdesk.com/support/login
Thanks will do. I thought I left the back panel off, to mitigate heat. Apparently I didn't .