Cordless vacuum will not power on, display shows E01 or single blink pattern on battery indicator

Safety first: Turn the main power switch off and remove the battery pack from the vacuum. Never attempt to open a lithium‑ion battery pack; risk of fire and chemical exposure.

• Check battery charge: Insert the Bosch battery pack into the original Bosch charger (e.g., Power for All 18V charger). Confirm that the charger LED turns on and does not flash an error. Allow at least 2–3 hours of uninterrupted charging.
• Clean contacts: With the battery removed, use a dry cloth or a cotton swab slightly dampened with isopropyl alcohol to clean the metal contacts on both the battery and the vacuum’s battery bay. Let them dry fully.
• Test with another pack: If available, try a known‑good compatible Bosch battery pack. If the vacuum powers on normally, the original pack is defective and should be replaced.
• Inspect battery bay: Check for bent, recessed, or burned contacts in the vacuum’s battery compartment. Do not bend contacts aggressively; if they are damaged, the handle/control module may need replacement.
• If E01 persists: Replace the battery pack with a genuine Bosch lithium‑ion pack. If a new pack still shows E01, the internal power/control PCB in the handle is likely faulty and should be serviced by a technician.