Cordless vacuum shows E4 or four-bar error icon; unit will not start or shuts off immediately; battery LEDs may flash abnormally.

Safety first: Do not attempt to open the battery pack. Lithium-ion batteries can be hazardous if punctured or shorted.

• Allow battery to cool: If the vacuum stopped during heavy use, let the battery cool at room temperature for 30–60 minutes.
• Check charger and contacts: Inspect the charging base and battery contacts for dust or corrosion. Wipe gently with a dry cloth. Ensure the charger is plugged into a working outlet.
• Attempt a full charge: Place the vacuum on the charger or insert the battery into the charging dock. Leave it charging for at least 3–4 hours, even if LEDs behave unusually.
• Observe LED indicators: Refer to your Eufy manual for LED patterns. Rapid flashing or no lights at all after several hours often indicates a failed battery.
• Try another outlet or charger: If available, test with a known-good Eufy charger to rule out a charger fault.
• Replace the battery pack: If E4 persists and the vacuum only runs for a few seconds or not at all after charging, replace the original Eufy battery pack with the exact model specified for your cordless vacuum.
• Contact support if under warranty: Do not use third-party or modified battery packs; they may damage the vacuum or create a fire risk.