DIAGNOSIS This is a loss of power. The most common cause is the circuit breaker on the mower tripping from overload or a clog.
FIX Step one: Unplug the mower. Locate the red reset button on the rear of the mower housing, near the power cord. Press it firmly. It will click. Step two: Check the extension cord and wall outlet. Plug the mower directly into a known-good outlet. Step three: Press the safety start lever and the power switch. It should run.
IF THAT DIDN'T WORK The 13-amp thermal fuse inside the motor housing may have blown. This requires disassembly to inspect. Contact Sun Joe support for a replacement part or service.
HEADS UP Always use a heavy-duty 14-gauge extension cord, minimum. A lighter cord will overheat, cause voltage drop, and can trip the internal breaker.