You need to immobilize the blade hub. First, disconnect the battery.
- Tip the mower on its side, air filter side up.
- Place a block of wood between the blade and the deck to stop the blade from turning.
- Use a socket wrench to remove the prevailing torque hexagon lock nut (part number 5630351002) that secures the blade (multiple blade part numbers apply, e.g., 3707494002).
- Replace the blade and the lock nut, tightening it securely with the wrench while the blade is blocked.
If that didn't work, ensure you're removing the correct fastener—the blade is secured with a lock nut, not a standard bolt.
Heads up: Always wear heavy gloves when handling the blade. The edges are extremely sharp.