My phone prompted me to do an urgent update yesterday morning, and since then it has developed some major problems. The biggest issue is that it thinks there is no SIM card inserted, so I can't make calls/send texts/use mobile data.
However, there also appears to be bugs elsewhere - for example, if I try to check for new software updates in Settings', it does nothing for about 10 seconds and then says "An unknown error has occurred. If this problem persists, restart the device". Under 'Last Update', it's greyed out and says "There's no information about this update" - so I don't even know what was changed. I also keep getting sporadic and different warnings when using e.g. Facebook messenger.
I am really frustrated, as I have tried restarting, rebooting in safe mode, clearing various caches etc. but I still have no network signal. I'm worried I've permanently broken my phone.
Please may I ask for any suggestions about what to do? Would a factory reset help with a software problem? I really regret updating, I have been so happy with the phone until now.
The phone model number is SM-G975F, One UI version 2.0, Android version 10.
Thanks everyone for the suggestions. I eventually solved this without needing to resort to factory resetting - I downloaded Smart Switch and when I connected my phone, it prompted me to do another software update. It took three hours to download and install, but I now have phone signal again! I guess something went wrong during the previous update and a fresh installation has helped.
The smart switch method was a life saver! Got into a similar situation of flight mode stuck between on and off states and no cellular connectivity. Upgrading the phone through smart switch did the trick. Thanks for this suggestion.