If the MFD touchscreen is dark, check to see if the energy-saver button is lit up green. All Xeroxes go into low-power mode when they’ve not been used for a period of time, and for some models, even the card-swipe will not respond until the machine has been ‘woken up’. Press the energy-saver button to wake the machine, and then swipe your card.
If the energy-saver button has no effect, check that the machine hasn’t been powered off, either at the plug or on the device itself. All devices are meant to be left powered on at all times, but occasionally staff do switch them off. The older 57-series and the big ColorQubes have a small switch on the left-hand side of the body of the machine. The 8900s have a rocker switch on the back of the machine above the power-cable. The 58-series machines have a combined energy-saver and power button – press briefly to take in/out of low-power mode, and press and hold to power up/down. The 75/78-series have a rocker switch on the front of the machine beneath a clear plastic guard.