F1 appears when water fills the base pan. When it happens, a Styrofoam float activates the flood switch.
Disconnect the dishwasher from the mains. Take off the bottom kick panel and dry the base pan using a large rag, sponge or towel. There may be water in the overflow pan, underneath the machine, or in the bottom part of the cabinet.
Or, you can get the machine out of the cabinet, tilt it back 50-60 degrees and hold it this way until all water drains from the bottom section. Get your rags, towels and tubs and/or buckets ready.
Open the device’s door and look inside. There will be stainless steel panels on the walls and door with screws. If these screws get loose, there may be leaks. Tighten the screws.
After that, put the bottom kick panel back in its place, fix the machine in the cabinet again, connect it to the mains and run a cycle. Most likely, it is going to work ok. If not, call a technician.