Safety first: Disconnect power before removing the front panel.

Dry the interface: If the keypad has been exposed to rain or condensation, gently dry the surface and surrounding area.
Inspect cable: Check the ribbon or harness between the keypad and main PCB for secure connections and no visible damage.
Test buttons: With power restored, press each button to see if any are unresponsive or stuck. Avoid excessive force.
Replace keypad module: If certain keys do not work or E18 persists, replace the user interface module with a Hewalex-compatible part.

Display shows E18; unit may not respond to keypad inputs.

Possible Causes