The safety switch actuator or the main electric assembly is faulty. Check the switch box set first.
- Inspect the switch actuator (part number 3129714001). Ensure it's not broken or jammed.
- Check the film switch (part number 4870710001) inside the handle assembly for damage.
- Verify the connections on the internal wire assembly (part number 2826843001) in the handle.
If that didn't work, the issue is likely in the power unit. The 4907.1 main electric assembly (part number 2830569003) or the 4908 fuse PCBA (part number 2830216002) may have failed. These require replacement.
Heads up: Never bypass the safety switches. The mower has a blade control system that must be functional.