V Minion bed heater issues

V Minion been working fine for months and 1000+ hours. Last week I tried to print and I got not heating errors... sure enough my bed isn't heating at all.

Things I've tried:
- reseated heater wires
- confirmed thermistor is working (to the best of my abilities)
- checked the thermal fuse (continuity is fine)
- checked the bed fuse (continuity is fine)
- measured output power on the bed when set to 100% power - and got 5 volts!?!?

I'm guessing it's something to do with 5 volts being sent to the bed, but I'm a little stuck how to go from here. What else can I troubleshoot? Is there anything I can do other than replace the mainboard and hope that fixes the issue?