What do the LEDs on the 3-in-1 card reader mean?

Here is the significance and usage of LEDs on the 3-in-1 card reader

• First LED flashing - the device is connecting with your smartphone/tablet
• First LED on - ready for use
• 4 LEDs on in consecutive order - successful reading NFC payment
• One "beep" sound - the transaction is complete
• Two "beep" sounds - indication there was an error
• All LEDs off - power is off or no power