I had the issue that my A4M2 1.51 did not boot up and froze on the logo screen. I updated the firmware in Recovery Mode to 1.51C. I now see 1.51C at the boot up screen, but it is still freezing at the logo screen. I upgraded once more to 1.51C but no success.
I tried the factory reset via FUNC and 4, but no success.
Any ideas?
have you another compatible power supply you can try it with? (needs to be the same model)
Yes. Just tried it with my AR power supply. Same result. Freezing up at logo screen.
ahhh. hopefully you get sorted 
After opening a ticket with Elektron it seams I have to send it in for repair. Since I am in Thailand right now that will be a project to get it through customs twice. But I don’t think I have an alternative.