I was mucking around trying to get an eSIM to work (not concerned about this now) in the process of which I turned off my usual SIM. The slider icon didn't change to the 'off' position, but since then the SIM hasn't worked and I haven't been able to turn it on. The airplane mode icon on my Samsung Galaxy A54 5G has been semi-lit since then.
I have:
Restarted the phone
Turned airplane mode off and back on
Removed and replaced the SIM while the phone was off
Performed a soft reset
Contacted Samsung, who are insisting I talk to iD before proceeding
And as far as I can tell this is the only way I can get help from iD