Cordless vacuum will not power on, battery LEDs flash rapidly in a repeating pattern when the power button is pressed.

Safety first: Disconnect the charger from the mains before handling the battery. Do not open or puncture the battery pack; swollen, hot, or leaking packs must be disposed of safely.

• Step 1 – Inspect the battery and contacts: Remove the battery pack from the Princess cordless vacuum (if removable). Check the metal contacts on both the battery and the vacuum handle for corrosion, burning, or bent pins. Clean light oxidation with a dry cloth; do not use liquids.
• Step 2 – Attempt a recovery charge: Place the vacuum on the original Princess charging dock or connect the original Princess charger. Leave it connected for at least 3–4 hours even if LEDs do not immediately change. Some BMS boards need a long, low‑current wake‑up period.
• Step 3 – Check charger output: With a multimeter set to DC volts, measure the charger output (without the battery connected). Compare to the voltage printed on the charger label (usually around 21–30 V DC for Princess cordless vacuums). If there is no output or it fluctuates heavily, replace the charger.
• Step 4 – Test with a known‑good battery (if available): If you have access to another compatible Princess battery, install it and try to power on. If the vacuum works, your original battery pack or its internal BMS is defective and should be replaced.
• Step 5 – Replace the battery pack: If the pack will not hold charge or the E1 indication persists after a full charge, purchase a genuine Princess replacement battery pack specified for your model. Slide the old pack out, insert the new one until it clicks, then fully charge before first use.
• When to stop: If the battery becomes hot, swells, or emits odor during charging, unplug immediately and do not reuse. Contact a service center for safe disposal and replacement.