My 60D (with ML installed) stopped working whilst I was taking photos - it showed err 80 on the LCD. Since then, the only sign of life from it was it once flashed an empty battery symbol on the LCD. I have tried all combinations of lens attached/removed and new batteries with/without old and new SD cards (both bootable and non-bootable) and the camera shows no outward response. The camera does not respond to the portable display test or LED blink test.
Any suggestions?
If you properly used portable display test with a bootable card (= remove battery, insert card, insert battery, close battery compartment door. If there is a battery grip attached: Remove it first) there is only a minor chance for some mechanical error involved. Check battery compartment door switch.
If there is no display message/LED activity ... well, bad luck.
Door switch appears to be okay... Canon no longer service the 60D, so I guess time for a new camera :(
ERR 80 is some error coming from the MPU. The battery icon is also controlled by the MPU. Since it's not blinking the SD LED when starting with a ML card, and it's not reacting to portable display test, that probably means the bootloader is unable to run, for some reason. I don't have the knowledge to diagnose this defect, sorry.
The case is similar to this: https://www.magiclantern.fm/forum/index.php?topic=17595
So, I'm afraid you were right about the new camera - unless somebody who knows how to fix this defect is going to prove me wrong.