How to Fix / Troubleshooting

Safety first: Turn off the vacuum and remove the battery pack. Do not attempt to open the battery casing.

Inspect the battery contacts on both the pack and the vacuum handle for corrosion or burn marks. Clean gently with a dry cloth.
Ensure the battery is fully seated and latched into the handle or body.
Fully charge the battery on the original Roidmi charger until the indicator shows 100%.
Test the vacuum on low, then medium, then MAX. If E4 appears only on higher power, the battery pack may be weak.
If the battery becomes excessively hot or E4 persists, replace the complete Roidmi lithium-ion battery pack. Do not bypass or modify the BMS.

Vacuum runs only on low power or shuts off when switching to MAX; display/app shows E4.

Possible Causes