Hantek DSO5102 CH1 issue and self calibration error x502

[MarkM]

I bought this scope quite awhile ago second hand, but I've barely used it.  I noticed when testing today that CH1 reads about ~400mV higher than it should.  CH2 reads correctly.  I tried using other probes.  Another issue is it won't self calibrate.  I tried it after it was warmed up as well as when cold.  No difference.   It comes up with the x502 error.

Google search comes up with people with the same issue, but no real solution.  I haven't cracked it open yet to check it out, but I'll post up when I do.  Any ideas for now would be greatly appreciated.  It'll probably take me a few days to get to it.