DIAGNOSIS Yeah, this one's common. During assembly, there's a critical step where you connect the drive cable to the rear wheels that people often miss or do incorrectly.
FIX You need to access the rear wheel assembly. Tip the mower back (remove the battery first). Look where the drive control lever on the handle connects via a cable to the transmission on the rear axle. The cable needs to be routed correctly and the retaining clip must be fully seated into its slot on the wheel gearbox. has a very specific diagram for this. It's fiddly—if the clip isn't in, the wheels won't engage.
IF THAT DIDN'T WORK The self-propel system has a shear pin that protects the gears. If you hit a huge obstacle, this pin can snap. You'll have to replace it. Check for a broken plastic pin in the wheel hub assembly.
HEADS UP Even when correctly assembled, the self-propel on this model is speed-controlled by how far you press the lever. It's not an on/off switch—press it further for faster walking speed. A light press gives a very slow creep.