Due to a not-given compatibility with Makerbot mechanical endstop wiring (and carelessness on my side) I ended up burning the voltage regulator on my Arduino Mega 2560. Now, powering the Arduino separately from a USB power supply, I can operate the electronics, however, I am still unable to receive any signal from the endstops and I don't want to hook up my replacement Arduino until I see that my wiring is correct.
Could I have burnt anything else on either the Arduino (pullup resistors were firmware disabled) or the RAMPS 1.4 which makes it impossible to receive a singal from the endstops?