Solved Anyone know what this hardware error pop up means?

Huh, so this is weird. I swapped thermistor positions on the RAMPS board and the bed still reads 21.9C. So the new thermistor I installed is OK. The bed thermistor that is now connected to where the hotend thermistor goes is now reading 85.9C. What does that mean? Something on the RAMPS board has blown/gone bad?

 

Dang, that stinks. I guess I'll have to pick up a new board. Thanks for all the help.

 

I'm actually going to have a go at doing that. I'm an Arduino guy, so it should be easy to do now that I've taken a look at this board and know what I'm up against.

I also have a spare Mega that I can pop on the board and see if that does the trick. I'm thinking the RAMPS board might be ok because I'm not really seeing much in terms of electronics on here. I don't see anything around the header that looks like it's blown. I might just connect my Mega and see if it works. If it doesn't, then it's definitely the RAMPS board that's somehow toast.

 

Sounds very familiar!
I had a similar issue going where my COLD hotend thermister read 230c.
Turned out to be the Arduino.

 

I installed a new EPCOS 100k thermistor and swapped out the stock Arduino with a new Mega. It works now. The extruder thermistor now reads 25C at room temperature. The one strange thing is that the first print job I printed stopped right after the bed-leveling routine. I checked the log and it had the same hardware error as before. I cleared the error, power-cycled the printer, and started again.

It's now printing, so I hope all is good. I'll just have to do a few more prints and keep my eye on it. I really hope I fixed it this time. I can't imagine what else it could be other than replacing the RAMPS board.