Safety first: Remove the battery and disconnect the charger. Do not short the battery terminals.

Reseat battery: Remove the battery pack fully and reinstall it firmly until it clicks. Ensure there is no play in the connection.
Inspect contacts: Check the metal power and data contacts on the battery and inside the handle/battery bay for bent pins, corrosion, or contamination. Clean gently with a dry cloth or cotton swab and isopropyl alcohol.
Check battery type: Confirm you are using the correct original Logik battery model specified for your cordless vacuum. Third‑party or mismatched packs can trigger E4.
Test with another battery: If possible, test with a known‑good compatible Logik battery. If the error disappears, your original pack’s BMS is faulty and the pack should be replaced.
Inspect handle connector: If E4 persists with multiple batteries, the battery connector or control PCB in the handle may be damaged and require replacement by a technician.

Vacuum will not start and shows E4; sometimes occurs after battery removal or drop.

Possible Causes