Robot vacuum will not start cleaning and immediately displays E1 or beeps E1 pattern.

Safety first: Turn the robot OFF with the main power switch (usually on the side or bottom) and remove it from the charging base. Do not open the battery pack itself; Li‑ion packs can be dangerous if punctured.

• Step 1 – Hard reset: Turn the main power switch OFF for 60 seconds, then back ON. Place the robot on the charging base and allow it to charge undisturbed for at least 3–4 hours. Try starting a cleaning cycle again.
• Step 2 – Check charging contacts: Wipe the charging contacts on the robot and the Medion charging station with a dry cloth. Lightly polish with a pencil eraser if they are oxidized, then wipe clean.
• Step 3 – Inspect battery connection: Remove the bottom battery cover (usually held by 2–4 screws). Verify the Medion battery pack plug is fully seated in the mainboard connector and that no wires are pinched or broken. Reseat the connector firmly.
• Step 4 – Test on adapter: Place the robot on the dock and confirm the charging LED on the robot and/or dock illuminates. If the robot still shows E1 after a full charge, the battery pack or its protection board is likely defective.
• Step 5 – Replace battery: Obtain a compatible Medion robot vacuum Li‑ion battery pack (check model number printed on the old pack). Install it in the same orientation, reconnect the plug, secure the cover, then fully charge before use.
• When to stop: If the robot smells of burnt electronics, becomes hot while charging, or the battery is swollen, stop using it and contact a professional or Medion support.