Can't configure APN/Have no mobile internet

[zvavybir]

My PinePhone worked great until (I think – this was quite some time ago because it wasn't urgent to get fixed, so I don't perfectly remember it anymore) it crashed and I had to force a reboot (taking out the battery).  Now the SIM card related stuff doesn't work (great) anymore.  To make or receive a phone call I now have to run `mmcli -m any -e` (found on the internet) to activate the modem (which isn't great, but also not a big problem) and (more importantly) I can't configure an APN (the option in the settings GUI is grey out, and I don't know how to do it in the terminal), which means I have no mobile internet (which wasn't a problem, because I'm usually somewhere with WiFi, but soon will be a problem).

It might (or might not) be worth mentioning that I somewhat damaged the SD/SIM card slot, but I don't think this is related, because it still worked for some time with this damaged slot and because after running this command making phone calls still works.

1) Make sure your internet provider is supported[1] (swapping SIM cards quickly from one phone to another may cause problems on the provider side)
2) Have you updated your OS? 
3) If your provider is supported and the OS is up to date, It maybe time for a fresh install of the OS[2].

[1] https://wiki.pine64.org/wiki/PinePhone_Carrier_Support
[2] https://wiki.pine64.org/wiki/PinePhone_S...e_Releases
EDIT: Link to Pro software releases
[2] https://wiki.pine64.org/wiki/PinePhone_P...e_Releases

1) It *used* to work, so the provider is not the problem.
1b) I haven't swapped the SIM card at all, so trivially also not quickly.
2) I have not updated it when it stopped working, so this can't have caused the problem.
3) That's of course is possible, but I'd *really* like to avoid it, because due to the SD/SIM card slot damage the phone is not guaranteed to work at all afterwards (if doing it would have been an option I of course already would have done so).