Got the grounding probe in yesterday so I am measuring 0 volts at this stage. Just need to get a new temperature controller. Debating if I will turn the powerhead back on.Hopefully that'll solve your issues once it's fixed
Good thing is this guys appetite is amazing and his personality is really coming out. He recognizes his "food plate" and tries to get it through the glass. When I was testing the volts in the water he came to the top and was hovering trying to eat the probes. I had to feed him so he would back off. Between some solid growth and great personality I really hope this was the issue and he heals. Don't have a ton of time for maintenance but trying to do 50% WC daily for the next week to help him heal.