Sidewinder X1 V4 reading 131C or 132C on both hotend and bed at power on

I have a Sidewinder X1 V4 that I upgraded to a Bimetel Heatbreak, MicroSwiss nozzle and a Wagster Mod BL-Touch. This has worked for about a year but recently I had a major filament meltdown (not sure if the Bimetal Heatbreak throat failed or if the nozzle became loose. The hotend ended up completely encased in PLA and needed to be replaced along with the thermistor and heater cartridge (and the heatbreak as well). After reassembling things I’m now having a new problem I can’t figure out. When I power up the printer both the hotend and bed temps are showing temps around 131C or 132C (instead of something like 20C). Even if I completely disconnect the hotend ribbon cable both temps always show 131C or 132C. With the ribbon connected I can get fans to run and my Wagster Mod BL-Touch works fine. Because both the hotend and bed temps are showing these weird incorrect temps I’m thinking this doesn’t have anything to do with the hotend electronics. Even with the thermistor unpluged from the board the temp still reads 131 or 132C (I would expect 0C when unplugged).
Also, I can actually set the temp on the hotend and it heats up. After 10 seconds or so the temp starts going up from the base 131-132C and will settle in on the temp I set. I have no idea if it’s truly heating to the actual temp I set but it IS definitely heating up. When I stop heating the hotend the temp reading will gradually return down to 132C when it’s fully cooled.

I’ve confirmed this has nothing to do with the hotend assembly at all. I get the same result (both hotend and bed show temp reading of 131C or 132C) even if I completely disconnect the hotend ribbon cable. I know from experience that if this was the hotend thermistor I’d see a temp of -15C. I’ve verified the power supply is good so now I’m starting to think the main controller board has somehow failed.

Any ideas??