If you see F35 on your washer’s display, there is a problem with the analog pressure sensor. It is a device, which measures water level in the tub. Not unlikely, the error will disappear after resetting. However, if the sensor is faulty, the error will continue.
The error occurs due to a faulty air pressure tube. Unplug the washer and check the tube: it is located between the pressure sensor and the bottom of the washer. To access it, remove the top panel: unscrew the back of the panel (there are two screws), pull it back, up and off from the machine. See the first image below: the analog air pressure sensor is Key 38. Make sure the air tube is properly connected to the sensor (unplug the machine!) Remove the back panel and check the tube for kinks, bends, tears, blockages, etc. If the tube is ok, not unlikely, the pressure sensor needs to be repaired or replaced. If the sensor is all right too, there may be a problem in the main control board, and it may need to be replaced. Please, do not try to repair the machine yourself if you do not have experience with this kind of device. Call your local maintenance service and use professional help.