I flashed Marlin onto the board without issues. If I plug the board only to the laptop USB, the display comes on normally and allows you to browse through the menu etc.
If I plug the board to the MPCNC (12V P/S), when I turn it on, the display turns on, but it alternates between dim and bright, each time only showing the “Marlin” logo, and keeps doing that over and over.
I have 2 sets of power going to ramps board as suggested. Do I need to power the arduino 2560 underneath it seperately?
Any idea what might be happening?