Been looking all over for a solution to the dreaded ER05 for my beloved UM2. It was kind of touch and go for a while, every other print would give me that error (I usually just unplug it for a while and start it up again), but last night it fully decided it wasn't going to print.
The switch is definitely working (tested with a Multimeter), motherboard looks fine, tightned any potentially loose connections. Having a hard time figuring out what it could be. I tried a factory reset, and now I'm just stuck in the intro screen because the bed won't go through it's calibration dance.
If it's any indicator, I replaced the motherboard with one from ebay a few years back. These past two months I've been printing probably about once a week at a minimum, and am planning on ramping up production pretty significantly (I am a student, and this is currently one my my primary means of producing).
I've got about a month to sort this before my school term starts again. Any ideas?