The F22 on a Vaillant boiler normally means that your system water pressure is low and would not suggest a dangerous fault nor anything to do with the electrics.
Have a look at the pressure guage and my guess is that it will be reading 0.3bar or lower, its needs to be reading 1.5bar.
If this is the case, and you are not familiar with topping up the system pressure, reply on this thread and I will provide a guide on the process to help you.

Rupert
March 2020