Vacuum does not respond to the trigger or power button; F4 is displayed, or the LED flashes rapidly when the battery is inserted.

Safety first: Remove the battery pack and disconnect the charger. Do not continue to operate a unit that has been exposed to liquids.

• 1. Power reset: Remove the battery for at least 5 minutes. Press and hold the power button for 10 seconds (with the battery removed) to discharge residual power. Reinsert the battery and test.
• 2. Inspect for liquid damage: Check around the handle, display, and battery compartment for signs of moisture, corrosion, or sticky residue. If liquid ingress is suspected, do not attempt to use the vacuum. Internal components must be inspected and cleaned by a professional.
• 3. Check wiring harness (visual only): If accessible without disassembly (e.g., at the battery connector), look for pinched or damaged wires. Do not pull on wires.
• 4. Firmware / PCB issue: If F4 persists after a reset and there is no visible damage, the main control PCB is likely defective. This requires replacement of the handle or motor unit assembly by a Miele service center.