Similar issue to the post above.
A bit of history on the unit. It was working fine and then it stopped mid print and screen shut off. Upon cycling power, the screen would not turn on unless I also plugged in the USB. Did a bit of research and saw that the supplied SD card often goes bad so I bought a new one. It is one of those SD minis that adapts to the full SD card if that matters. Did some partitioning and reformatting and all that. Got the firmware updated (.bin changed to .cur).
Then, during an overnight print, I ran out of filament and I did not catch it in time. Tried to restart in the morning, but the nozzle hit the part and it easily unstuck itself. After it cooled down for a few hours, I tried to turn the unit back on and the screen will not turn on like before. I then plugged in a USB and the screen works. Except I now notice that the bed heat was high and forcing it to cool did nothing.
Did another firmware reflash (.bin changed to .cur). Still the screen will not turn on unless a USB cable is plugged in. Sliced up a quick 30 second print file and I prints (with the USB plugged in) but the bed heat still always goes up regardless of what target it is trying to hit. The reported temperature does seem to be fairly accurate but once it passes 70C, I shut it down.
I then found the post I linked above and did a powered off ohms check on the two points on the connector and read basically 0 ohms. Powered the unit on, and read 21.5 volts.
Is there anything else I should try before submitting a request for replacements?
PS - Not sure if the history adds any helpful info, but I thought I’d include it as I’ve only had this for 2-3 weeks so it was fresh on my mind.