Cordless vacuum beeps and shows E9; unit will not start after being stored in a cold or hot environment

Safety first: Do not attempt to heat the battery with external heat sources or cool it in a freezer. Extreme temperatures can cause battery damage or fire.

• Step 1 – Normalize temperature: Bring the vacuum and battery indoors to a room-temperature environment (20–25 °C). Leave it unplugged for at least 1 hour.
• Step 2 – Try charging again: After the rest period, place the vacuum on the charger and observe if charging starts normally.
• Step 3 – Inspect battery pack: If the pack feels unusually hot during or after charging, remove it (if removable) and let it cool. Do not continue using an overheating pack.
• Step 4 – Persistent E9 at normal temperature: The NTC sensor inside the battery pack or the sensing circuit on the main PCB may be faulty. Replace the battery pack first; if the issue remains, the main PCB likely needs replacement.