Nothing wrong with my Samsung Galaxy S9 plus but I had to upgrade because of some work related apps. Now my S9 plus would not unlock. Tmobile tried and say it is unlocked at our end, try a different carrier sim and it would work. I don't have any other network sim and my phone (bought new from Samsung and paid fully) would still show it is locked. Any help?
Is it showing locked, or is it just booting with the T-Mobile logo? Two different things. Just because your carrier unlocked the phone, does not mean the firmware changed, it would still have their logo and software on it, unless you replace the firmware. If T-Mobile says it's unlocked, it probably is. Borrow a SIM from someone who is on a different carrier to insert and see if you get a mobile signal. If you do, the phone is unlocked.
In your T-Mobile app or account, go to manage your devices and tap on your device. In the Status section it will have a section for Device unlock status. It will either say locked, unlocked, or unknown. If it says unlocked, it's unlocked. As I said before, just because it boots with the T-Mobile logo and tune does not mean it's locked. Even though you got the phone directly from Samsung, it was still loaded with the carrier firmware and will still have that even after being unlocked. There are ways, I hear, to replace the firmware, but a) I don't know how, and b) I, personally, wouldn't mess with it, lest I end up with a brick. There are people on this app with experience doing that, and you might make a new post asking that question, as they might not see the question here if you ask in this post.
