DIAGNOSIS The mower has lost the boundary wire signal. This is usually a break in the boundary wire or a poor connection at the guide wire.
FIX First, check the LED on the charging station. A steady green flash means the station is sending a signal. If it's off or solid, the station has an issue. If the station is okay, visually inspect the area where the mower stopped for a cut or chewed wire. Use a wire break locator tool for buried breaks.
IF THAT DIDN'T WORK The connection points at the charging station (AL and AR terminals) can corrode. Disconnect, clean the wire ends, and reconnect tightly.
HEADS UP A break in the boundary wire is the most common installation fault. Splices must be waterproof. Poor splices cause intermittent 'no loop' errors.