The control board needs time to discharge its capacitors. The 20 seconds should do it, but. No offence, but wait for it to cool down and try turning it off for a minute if you have not.
Some pyrolytic ovens have a problem whereby they try to unlock the door while the oven is too hot and the lock/unlock motor is not strong enough to overcome the hot latch, hence the error. The control boards are not smart enough to reset but when the power is removed for a sufficient time they reboot when powered up again, then they do a system test and unlock the door in the process. If that does not happen you have either a failed control board ($$$) or a failed lock/unlock motor ($).
Edit: Electrolux F08 is a ‘communications failure/power supply error’ with the repair to check internal wiring and replacing the control board. It can be a long shot that an internal connector has degraded from heat over time, but. Another instigator of problems can be a degraded fan causing overheating causing something else to malfunction.
I had a higher end pyrolytic that we recently sent to the tip after only 6 years rather than keep fixing it. At 4 years pretty much everything except the frame and heating elements were replaced under the ACL. In year 6 it started behaving erratically and bought a SMEG pyrolytic that is 2 months old; other than a teething problem out of the box it has been surprisingly pleasant and SMEG service has been faultless. The previous manufacturer completely redesigned their product and it is now sold under a different brand so I’ll not mention the name here.
The reason pyrolytic ovens can be unreliable is they heat to 400-500C and there are electronics packages controlling them. Electronics dislike heat, hence the fans in all modern ovens to keep the controls cool.
I recommend anyone with a pyrolytic oven runs the cycle monthly to be sure it still works. In our experience failures are most common after running a cleaning cycle.
If you wish to pursue a repair under the ACL you have to work under the law as it was in 2010, eg whatever your state equivalent was before 2011, so you do not have the same eights as with my 1-year later purchase.
If the cool down and power cycle works, please post it. Otherwise your choice is probably a repairman or a replacement. Some owners get the door unlocked and just stop using the pyrolytic cycles and the ovens cook just fine, although hand cleaning them can be troublesome