Display shows E9; vacuum may not respond to power button or may shut off randomly; sometimes accompanied by flickering display.

Safety first: Turn OFF the vacuum and remove the battery. Do not continue to power-cycle rapidly.

• Soft reset: With the battery removed, press and hold the power button for 10–15 seconds to discharge residual power. Reinsert the battery and try again.
• Check for moisture: Inspect the handle and display area for signs of liquid ingress. If the vacuum was exposed to water, allow it to dry for at least 48 hours in a dry environment before retrying.
• Inspect buttons: Ensure the power and mode buttons are not stuck or physically damaged. Gently press each button several times.
• Update firmware (if supported): Some Eufy cordless models may support firmware updates via app or service. Follow Eufy’s instructions if available.
• Service main PCB: If E9 persists and the unit behaves erratically, the main control board likely needs replacement. This involves opening the main body and should be done by a qualified technician.