Battery indicator flashes rapidly and the vacuum will not start; E06 or a battery fault icon is displayed.

Safety first: If the battery feels hot to the touch, do not attempt to charge it. Place it on a non-flammable surface away from flammable materials.

• 1. Allow cooling: Let the battery cool at room temperature for at least 1 hour. Do not place it in a fridge or freezer.
• 2. Inspect battery: Check for swelling, cracks, or leakage. If any deformation is visible, discontinue use immediately and dispose of the battery according to local e-waste regulations.
• 3. Clean contacts: Wipe the battery and vacuum contacts with a dry cloth. Ensure there is no moisture or corrosion.
• 4. Attempt recharge: After cooling, place the battery on the Grundig charger. Observe the charger LED. If it flashes an error pattern or E06 persists, the internal temperature sensor or protection circuit is likely faulty.
• 5. Replace battery: Obtain a genuine Grundig replacement battery pack. Do not attempt to open or repair the old pack. If a new pack also triggers E06, the fault may be in the vacuum's battery interface PCB and requires professional diagnosis.