Did you run the crown from the SD card or repetier, try doing it the other way.
Can you plug just a single stepper in on your X and Y and not use the wiring harness. Also to be safe can you put the board on something other than bare wood, even the bag it came in would be a better choice, just to be safe.
Just to give you some background, typically either they don’t move at all, or just the commands are wrong meaning my gcode makes it work perfect. You are getting sporadic issues which has never happened to my knowledge. You have a valid LCD screen meaning it should be the right firmware, you put a meter on your power supply, and you can connect and send commands. This makes no sense.
Using the Repetier software with laptop I ran the “Crown” gcode and it completed the entire program 2 times on the 3rd time it failed on the x and y halfway through the program. The “one” X, “one” Y & Z steppers are plugged directly into the board “no cable extensions”.
I ran the “Crown” gcode on the SD card X and Y do not rotate but the z is working. The “one” X, “one” Y & Z steppers are plugged directly into the board “no cable extensions”.
I believe I loaded the firmware correctly. I tried running the Crown “gcode” and received the same results. The gcode runs and the X & Y do “not” rotate Z is working correctly. screen images below
Just to be sure keep your fingers on the X and Y pulleys. At times they will not move much and the file should be about 5 minutes long. You said it does work all the way through from repetier sometimes? When using the LCD you have the USB disconnected correct? Power supply says 12V the whole time or is it browning out maybe?
If you are positive something is wrong send it in and I will test it. Still is not making any sense but doesn’t mean you are wrong, so feel free to send it in or we can trouble shoot more. Up to you.