Apple iPhone 14 Activation Problem

Apple iPhone 14 Activation Problem, I first called Apple support on 27 February 2023, stating that the Apple iPhone 14, which I bought from abroad on January 8, 2023, from the Apple UK Watford store, started to have problems communicating with the GSM operator after the last update, and after I exited iCloud to restart the phone, the phone remained on the activation screen. They told me and e-mailed me that this is a problem encountered and the instructions I need to follow for activation over Wi-Fi. In this meeting, I repeatedly asked and confirmed whether the software update step is a process that affects the warranty, and they said no. Both solutions offered in the email did not help to fix the problem and I delivered the device to Apple Gordion Troy service on February 28, 2023. When it was delivered, the device was checked and received, and the physical condition of the device was checked by the service person, so it was not possible to go beyond the activation screen. However, today, on April 1, 2023, when I contacted the Apple support line to learn about the status of the device, I reached the information that the device (sim module) would not be helped because of unauthorized intervention. I told the authorized personnel how meaningful the accusation of interfering with a device under warranty in a different place was, and I absolutely did not accept this situation. In this meeting, Apple hinted that the place I bought it from may have done this, but I have not reached a conclusion yet. The most serious thing was to be faced with an accusation of interfering with a device under warranty in another place or buying an interfered device from the apple store. I'm asking for help with the problem I'm experiencing, with all due respect.