Safety first: Remove the battery from the vacuum.

Allow the battery to cool at room temperature (20–25°C) for at least 30 minutes away from direct sunlight or heaters.
Do not place the battery in a refrigerator or freezer; rapid temperature changes can damage cells.
After cooling, reinstall the battery and test. If E8 appears immediately on a cool battery, the internal temperature sensor is likely faulty.
Replace the complete battery pack. Do not attempt to open the battery casing or bypass the sensor.

Vacuum shows E8 or a temperature icon and will not operate until cooled.

Possible Causes