Question from a passenger: is it correct that when the seatbelt signs are OFF during embarkation/pre-departure, this means the aircraft is being refuelled?

Seat belts must be undone whilst refuelling. If they're off that maybe one of the reasons but maybe I just haven't tured them on yet.

Confirmed.
New incident in a Ryanair flight.
Unscheduled stop in STN due to technical problems after departing from LBA.

Desvan a Alicante un avin de Ryanair que aterriz de urgencia en Londres. Las Provincias
Sorry, but no info in british newspapers