Robot mower will not start mowing; display shows E1 shortly after power‑up or when starting a job.

Safety first: Turn the mower's main power switch OFF and remove the battery if accessible before working on it. Keep hands away from the blade area.

• Check the red STOP button: On most Kress robot mowers the red STOP button is a latching type. Press it firmly once to ensure it is fully depressed, then press again to release it so it pops up. Turn the main power back ON and see if E1 clears.
• Inspect for debris around the button: With power OFF, look around the STOP button for grass, mud, or plastic deformation that might keep it partially pressed. Clean with a soft brush and compressed air. Do not use excessive water.
• Check top cover alignment: If the upper housing or service cover was recently removed, ensure it is seated correctly and not pressing on the STOP switch bracket.
• Test the switch (advanced): If you have a multimeter and experience, disconnect power, open the top cover, locate the STOP switch harness on the main board, and test continuity while pressing/releasing the button. Replace the Stop Button Switch Assembly if it does not change state.
• If E1 persists: The input circuit on the Main Control Board may be faulty. Contact a Kress service center.