Remember you can board with your QFF card domestically if your phone is dead
well yes and no.
You still need to have checked in which is one of the issues brought up above... but additionally....
At least in my experience.
For those with digital cards - fine - but then if you have the app and digital card you are not part of this "problem" set. (note my use of quotes).
For the physical cards.. well I came across a situation some months back when I used my 2019 issue card (the last physical card I got from QF) and the kiosk (RIP) threw up errors and would not check me in. Odd, as it had always worked prior to this. So I thought OK old kiosk needs replaceing and went to the lounge to check in. Handed over my card and the agents actually also had problems with it.
The explanation I was given was that the bardcode, or whatever it pointed to in the QF database had expired (which makes sense kind of given the original card expiry date was Aug 2020). Sure enough, digital BC is different to the physical card and so I suspect that a new record was created.
So my point being that it may work with physical cards for non status members, or perhaps LT status members (just a guess) but perhaps not for status members with now older cards.
Or it could have just been a glitch that day and I was being told porkies. you decide
anyway one still needs to have checked in via some method before going to board.