The green lights are on on the Arduino, but the green light on the Ramps is flickering constantly. I have reset and re-uploaded the firmware, but still getting the same results. Does anyone know what would cause the screen to flicker like this? The light on the RAMPS seem to flicker at the same frequency. I was having a few endstop short circuits recently (may be the problem). I have those chinsy 3-wire endstops that short circuit if you plug them in the wrong way.

Any help would be greatly appreciated. Thanks!

If you plug in an endstop the wrong way it is very likely you have damaged the voltage regulator on the mega

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Dust
If you plug in an endstop the wrong way it is very likely you have damaged the voltage regulator on the mega

How would I fix this? I measured the voltage earlier and it was all OK

The full graphic displays take a bit more power than the Arduino can provide. I had to add a separate 5 volt power supply to keep my Arduino running more than a few seconds with my display plugged in.