If the wrist stops operating properly and displays a communication error, there is one most likely cause.
The wrist has disconnected during use. Check the USB cable connections to the PC and restart the system.
If the error persists, proceed to check the USB connection to the wrist board (located inside the tower on the lower left of the back wall). If connected, the red LED on the board will be lit. Restart the system.
If E12 error persists, one or more of the USB ports on the PC may have been damaged during assembly or disassembly. Try using a USB multiport hub to connect the two usb cables to the mini PC.