Robot mower shows E4 and the cutting disc does not rotate.

Safety first: Turn off the main power switch and wait until all parts stop moving. Wear cut-resistant gloves before touching the blade disc.

• Check for obstructions: Carefully turn the mower on its side. Inspect the blade disc and surrounding area for branches, stones, or thick grass clumps. Remove all obstructions.
• Inspect blades: Ensure the pivoting blades on the disc can swing freely. Replace bent or rusted blades using original AL-KO blades and screws.
• Manually rotate disc: Gently rotate the cutting disc by hand. It should turn smoothly with slight resistance. If it is stiff or grinding, the blade motor may be failing.
• Clean underbody: Scrape off heavy grass buildup from the deck and disc. Excess buildup increases load on the motor.
• Test on shorter grass: Move the mower to a shorter, drier area and start a manual mowing cycle. If E4 clears, gradually resume normal operation.
• Electrical check: If E4 returns immediately, remove the cover and inspect the blade motor connector at the main PCB. Reseat it. If available, measure motor resistance and compare with AL-KO specs. Replace the blade motor if out of range or shorted.