First of all: does the card reader respond to the card?

• No response?
   Check if there is power to the system. The power must be at least 6 volts.

• Response, but no access?
   Then look at the message on the display of the card reader:

  • N04 – Card not in Whitelist
    The card is not (any longer) allowed. Add the card to the Whitelist if necessary.

  • E99 – Voltage below 6V
    The power supply is too low. As a result, the lock cannot be engaged.

  • Drum closing
    The system thinks the drum is still open. Check the slot sensor.

  • Drum opening
    Do you hear a click? Then the lock is being engaged, but there is likely something mechanically stuck in the drum. Check for a blockage or damage.