Cordless vacuum will not run, red LED flashes four times in a repeating pattern immediately after trigger is pulled

Safety first: Remove the battery from the vacuum and unplug the charger from the mains.

Steps:

• Allow cooling time: Place the battery on a non-flammable surface at room temperature, away from direct sunlight or heaters. Let it cool for at least 30–60 minutes.
• Check charging environment: Ensure the charger is used in a cool, well-ventilated area. Do not charge the battery in enclosed cabinets or on soft bedding.
• Inspect battery casing: Look for swelling, cracks, or burn marks. If any are present, discontinue use immediately and replace the battery.
• Retry operation: Once cool, reinstall the battery and try running the vacuum. If the error clears, avoid back-to-back full discharges and charges that can overheat the pack.
• Test with another battery: If available, try a second Hoover-compatible battery. If the second battery works, the original pack’s temperature sensor or BMS is likely faulty.

Important: Do not attempt to open the battery pack. If E4 persists with a cool battery, replace the battery pack or contact Hoover support for a genuine replacement.