The charger shows E19 and refuses to start; this is often associated with RFID or user authentication issues.

Safety first: Access control components are low-voltage but still require the power to be OFF before internal work.

• Test multiple cards: Try several known-good RFID cards or fobs to rule out a single faulty card.
• Check reader location: Ensure no metal objects or thick covers are obstructing the RFID reader area.
• Inspect connections: With the power OFF, verify the RFID reader cable is firmly connected to the main board.
• Re-enroll users: Using the app or local interface, clear and re-add authorized users/cards.

If the reader does not respond at all or E19 persists, replace the RFID reader module with a compatible United Chargers part.