iPhone 14 Motherboard Failure After One Year - No Repair Under Warranty

The motherboard of my iPhone 14 has malfunctioned. I purchased the device in France in July 2023 and registered it to my passport on July 7, 2023. I used it without any issues for about a year and a month. In August 2024, the phone began to have problems—it still works but constantly shuts down and restarts on its own. I took it to an authorized service center where they determined that the motherboard was defective and did not charge me any fee. I also spoke with several independent technicians who confirmed that motherboard failure is a common issue in iPhone 14 models. I learned that the international warranty period is one year, so I sent the device to a service center in France. However, they refused to accept it, claiming the phone had been taken out of the country. The French service center then suggested sending it to the factory, which was done, but the device was returned to me without any repairs. I have no complaints about the authorized service—my complaint is about the manufacturing defect. I request that the motherboard issue be repaired free of charge or that the device be replaced. I kindly ask for my grievance to be resolved.