Recently, my unlocked S10+ randomly decided my SIM card is invalid. I ordered a new one from Consumer Cellular, but I still get the invalid SIM message. The SIM works fine in an old phone. But I really want my Galaxy to be my only phone and work for calls and messaging, which I obviously can't do right now. While I don't know if this has anything to do with it, I suspect it might: the phone was bought as an unlocked phone off Amazon, but it has Sprint software and the Sprint logo on bootup. That was not a problem for the first 9 months of having the phone before it decided the SIM was invalid. Anyone else have any such problems and know what to do about it? I've done everything I've read up to and including a factory reset, with no luck. I live a minimum hour's drive from any service center, and I can't afford the service at any rate, as Samsung says I'm out of warrnty (*just* out of warranty, mind you). I would be eternally grateful for help with this.