FAGOR FUS-6116 IT doesn’t start (F04 error)

Hi.

My washing machine (brand FAGOR, model FUS-6116 IT) has stopped working without warning mid wash. All it says since is “F04”, which according to the manual means the machine doesn’t start, although it doesn’t specify why. It does however suggest that it might be because the door is not shut properly – as far as I can tell the door is closing completely though – is it possible that the problem is indeed with the door, just something that isn’t immediately apparent?
Otherwise I have checked the pump filter and cleaned it to make sure there’s no blockage there (there was quite a bit of debris there), but not sure what to do next. I’d call some professional to have a look, but it isn’t very cheap so am trying to avoid it if possible (starting to think I just need to bite the bullet and do it!). If anyone has ran into the same/similar problem and have some ideas of what it might be I’d be very grateful if you could share it with me! I’ve put pictures below of the washing machine in question and the error on its display screen here: https://i.ibb.co/Sy1X0rK/Untitl22d.png
Thanks!