Vacuum will not power on; battery LEDs flash rapidly red when power button is pressed.

Safety first: Unplug the charger, power the vacuum OFF, and remove the battery pack (if removable). Do not continue trying to power the unit if you smell burning or feel excessive heat.

• Inspect the battery pack: Remove the pack from the handle or base. Check for swelling, cracks, burn marks, or corrosion on the battery terminals. If any are present, discontinue use and replace the battery pack.
• Clean battery contacts: Use a dry cloth or cotton swab with a small amount of isopropyl alcohol to clean the metal contacts on both the battery and the vacuum. Let them dry fully, then reinstall the battery firmly until it clicks.
• Reset the protection circuit: With the battery removed, hold the power button for 15–20 seconds to discharge residual power. Reinstall the battery and try powering on again.
• Test with another battery (if available): If a second compatible Tristar battery works normally, the original pack is defective and should be replaced.
• If the error persists with a known-good battery: The BMS inside the pack or the main control PCB may be faulty. At this point, replacement of the battery pack or main control board is recommended; internal board-level repair should be left to a qualified technician.