Vacuum will not turn on at all; no lights or sounds when pressing the power button.

Safety first: Do not attempt to open the battery pack itself. High-energy cells can be dangerous if mishandled.

• Check charger and outlet: Confirm the outlet works and the charger LED illuminates when plugged in. Try a different outlet if necessary.
• Charge fully: Place the vacuum on the dock or connect the charger directly and allow it to charge for at least 3–4 hours. Look for any charging indicators on the vacuum.
• Test with another battery (if available): If a second compatible Tristar battery powers the unit, the original battery is defective and should be replaced.
• Inspect for physical damage: Look for cracks, signs of impact, or burnt smell from the main body. These indicate possible internal damage.
• Internal diagnosis (advanced): If you are qualified, open the main body to check for loose connectors between the battery terminals and the main PCB. Reseat any loose connectors. If there is still no response, the main control PCB is likely faulty and requires replacement.