I have had an Ender 3 Pro for the last year, and put a BLTouch on it about 6 months ago. With the BLTouch installed for the last 6 months, I have successfully completed hundreds of prints with no issues.
Recently I was starting another print, and the BLTouch did not complete its leveling sequence fully and the print never started. Now sometimes it will lock up on the first probing point (1/9), it moves to the (x,y) point and extends the probe tip and then the Z-axis will move up and stop and then up and stop again. Other times it will complete the first probing points normally then lock up in the same way on point 5/9.
It does this regardless of if there is an SD card in the printer or not (starting a print or just navigating the menu). It will successfully complete the "auto home" sequence but not the "level bed" sequence.
For troubleshooting, I have tried a different leveling sensor I have and the same problems happen with it, so I don't think there is a problem with the BLTouch sensor itself. I have also flashed reflashed the firmware (Marlin 1.3.1), and that also did not solve the problem. My mainboard is the 4.2.2 model, and I have checked the plugs where the sensor gets plugged into the main board.
I am considering replacing the mainboard with the 4.2.7 model as my next step, but Im not sure that that will solve whatever problem is happening. Any ideas or tips would be awesome.