Vacuum will not start; LED on the tool flashes red rapidly as soon as trigger is pulled.

Safety first: Do not attempt to open the battery pack. Only use Milwaukee-approved chargers.

• 1. Check battery charge: Press the fuel gauge button on the M18 pack. If 0–1 bars, fully charge the battery on a Milwaukee charger until the charger LED turns solid.
• 2. Try another battery: Install a different, fully charged M18 pack. If the vacuum runs normally, the original battery is likely failing.
• 3. Inspect contacts: Clean the battery and tool contacts with a dry cloth. Ensure no metal shavings or drywall dust are bridging terminals.
• 4. Ambient temperature: If the battery is very cold or hot, let it return to room temperature and try again.
• 5. If multiple good batteries fail: The control PCB’s voltage sensing circuit may be defective. Have the vacuum inspected by an authorized Milwaukee service center.