F05 indicates the pressure switch is stuck on full.
As it hasn't drained this would suggest a blockage somewhere.
If it's not draining at all, check the drain hose where it connects to the house drains.
If it's onto a connection, take the hose off and check the hose and the connection for a blockage.
If ok, you'll need to manually remove the water from the machine.
Take the plastic cover below the front panel off.
Put a shallow dish in front of the filter/pump cover. (Bottom, front right).
(There may be a drainage tube, if there is, use that to drain the water off).
Slacken the cap a little to drain the water.
Tighten the cap to stop the water when you need to empty the container.
Once the machine is empty of water, take the cap off.
Clean out any debris in there.
Look into the pump housing and you'll see the pump impellor.
Ensure this can turn and isn't jammed by a small piece of debris.
Remove any laundry.
Put the machine on spin only.
Look into the open pump housing to see if the pump impellor is spinning.
If all ok, refit the cap and try the machine again.
Hope this helps
Let me know how it goes or if you need more help
There's something in the filter jamming it and preventing you unscrewing it.
Unplug the appliance.
Have someone hold the appliance tilted rearward.
If you're lucky, you'll have an open base and not a solid one.
Take the screws holding the filter chamber in place out.
Take the chamber assembly inside the machine and out the bottom.
Drop it out the bottom into a wash basin.
Take the wires off the pump.
Take the hoses off of the chamber. (water will come out).
Now remove the debris through the hose ports until you can get the cap off.
Clean it all out.
Reassemble the appliance.
Plug it in and try again.
Let me know how it goes
Thanks for coming back and letting me know how it went.
I'm glad you got it sorted out and working again.
Thank you for the kind words and praise, it is appreciated.
Good luck with the appliance.