There are 4 LEDs on the top of the Reader used to indicate progress of a transaction.

Blue – For contactless transactions, indicates that the Reader is waiting for card. The Reader will also beep, indicating you should swipe or tap the card.

Yellow – Indicates the Reader is reading the card.

Green – Indicates the card read was successful.

Red – Indicates a card processing error.

Note: The yellow and green lights turn on and off quickly.