So I have a (refurbished) S23+ is currently in One UI 5.1 (with its last security patch being from July 1st 2023), and I'm unable to software update it. Whenever I try to manually update it, it says the software is up to date, even when I try to update it via Smart Switch in my laptop.
It's fully unlocked and currently been used with AT&T, but it was originally a T-Mobile phone or at least that's what its IMEI shows me when I check it.
Has any of you had this issue before? If so, how did you fix it?
I tried it. I don't know if it is because the Sim Card is old or non-activated, but it didn't do anything. I think by this point the only choice left is to flash the software. Still, thank you for your help.
You can try removing the SIM card from and restarting the phone. If it still has the magenta splash screen, enable/connect to Wi-Fi and check for updates. If the magenta splash screen doesn't show anymore, do what @LongHiker recommended.
