Safety first: Unplug the dryer and verify the drum is cool before working inside.

Check drum movement: Open the door and try to rotate the drum by hand. It should turn smoothly with moderate resistance. If it is very hard to turn, the motor or drum support components may be seized.
Inspect belt: Remove the top panel and look at the drive belt. If the belt is broken or off the pulley, the motor may run but the drum will not turn (you may still see E51 if the control senses a fault).
Access motor and harness: Remove the front panel and lower access panel to reach the motor. Check that the motor plug is fully seated and that there are no burnt connectors.
Test motor windings: With a multimeter, measure resistance across the motor terminals according to the service manual. If windings are open or shorted, replace the drive motor.
Control board relay: If the motor tests good but does not receive power when Start is pressed, the motor relay on the main control board may be defective. Inspect the board for burnt spots; replacement of the board is typically required.

Because this involves high current circuits, if you are not comfortable testing live voltage, contact a qualified technician.

Dryer will not start; E51 displayed; sometimes a click is heard but drum does not turn

Possible Causes