The F-51 and F-50 error code on this washer indicates that the machine control board in the console detects a motor RPS (Rotor Position Sensor -- tachometer) failure. This can be caused by a number of different problems. You could have a bad RPS sensor, a failed motor, a wire harness connection problem or an item stuck between the spin basket and the outer tub that is interfering with spin basket rotation. A water filling problem could also cause this code to be displayed since the basket would have excessive friction if water is not entering the machine properly. With the washer off, spin the basket to see if it rotates freely. If you detect resistance or suspect that an item is stuck between the basket and the outer tub, you will likely need to remove the basket and check this area. The procedure for removing the basket is shown in the first image below. Remove the basket and check for foreign objects or debris.
If the basket spins freely, make sure that your water supply cut-off valves are fully open. Shut off the water supply and remove the hoses from the connections on the back of the washer. Place the ends of the hoses in a bucket and briefly turn on the water supply to check the flow and water pressure coming from the end of the hoses. Check the inlet water valve screens for deposits or debris that could interfere with the water fill. The motor will begin to spin the basket before the washer completes the filling function. If the filling is slow, it could cause the F-51 and F-50 code.
If the water supply is okay, you could have a wire harness connection problem, failed RPS sensor or a number of other failures. If you are technically advanced and have a volt/ohm meter, you can use the technical information provided in the third image to try and diagnose your likely failure. NOTE: This information is intended for technicians. Follow electrical safety guidelines when using this information. Unplug the washer to disconnect electrical power before accessing internal components. Internal metal edges in the washer can be sharp. Protective gloves are recommended.
I recommend that you unplug the washer and access the control board first. Check the wire harness connections on the P10 and P5 plugs first. Measure the resistance through the motor and the RPS sensor as shown below. This may point you in the direction of your failure. If you need more help, submit additional details.