I think you are correct in that the pressures of EU 261, if any, aren't relevant to this incident.
The investigation will no doubt be able to determine when that panel was last disturbed, and it's very unlikely to have been on a turnround.
It may or may not be relevant that the aircraft in question had a couple of 3-day spells on the ground at AMS at the end and beginning of August, possibly on some sort of maintenance input.
That panel doesn't look like it's been on the aircraft for all that long.