So I was printing a 0.75 k-factor test yesterday and went away for maybe 8 minutes and came back to a TFT screen where it's black levels were grey. Since that's out of the ordinary, I power cycled the printer and was met with "ALL LOW" messages, which I only get if there's something wrong with the TMC drivers. Soon after, the TFT went white. 

Confused, I turned the printer off for a few hours and the TFT seemed like it was working as normal but I was still getting "ALL LOW". In the notification, I had 3 of those messages. I took out all stepper drivers, cleaned off any offcuts of wire/plastic that I found resting on the Octopus board, and booted. The "ALL LOW" beeps sounded different, but I could only see a max of 5 in the notification menu; I assumed that there were more. I tried M122, both through the TFT and a PC, and the printer would crash midway through printout.

I plugged all the extruder drivers back and it was back to 3 messages. While I was putting them back, I noticed that one of the EXP connections was loose and pushed it back in, so my new hypothesis was that this loose connection manifested into symptoms. 

I plugged the stepper drivers on the EXP MOT back in and success! No "ALL LOW" messages and M122 worked without crashing.

Today, the TFT24 went white again, and it's been a reported problem:

1. https://github.com/bigtreetech/BIGTREETECH-TouchScreenFirmware/issues/254
2. https://github.com/bigtreetech/BIGTREETECH-TouchScreenFirmware/issues/523

Allegedly, the actual TFT is defective and a replacement is needed: