I am running my MPCNC with an Ender 3 Board through Proterface without an LCD and with no Endstops.
No Problems at all…at least with the board and driving the machine through it.
“But why no Endstops?” Easy: Use dual or don’t use any. Dual won’t work with that board so dumped them completely. A CNC doesn’t need them to do its work, apart from safety concerns (well… ¯_(ツ)_/¯ ) its more a 3d Printer thing, that we got used to. With a CNC your 0/0/0 is usually the corner of your stock and no endstop will help you find that. You can recycle the Pins for touchoff plate though (wip on my end).
The only files i edited are configuration and configuration_adv
If you dont wanna mess with the Firmware you can even run the machine with an untouched board. Just jumper the Endstops (they are NC by default) and disable software endstops (M211 S0).
More than enough for a quick test.