Samsung S25 Ultra Keeps Restarting - Service Claims ‘No Issue Found’

On September 1, I purchased a Samsung Galaxy S25 Ultra 512GB with Samsung Türkiye warranty through Trendyol, and from the very first day, the device has been constantly shutting down and restarting by itself. I experience this issue at least 10 times a day. I performed two factory resets, but the problem continued. At one point, the device even booted into recovery mode on its own, and I had to reset it again. I reported the issue multiple times through the Samsung Members app. The device received a new software update, but the problem was not resolved. I finally took the phone to the authorized Samsung service center and the device shut down and restarted in the technician’s hand during drop-off. I requested a device replacement, but for the past four days, they have been “testing” it and keep telling me “no issue found.” My invoice number is tys2025022669362. For two months, I struggled to use the device despite constant problems, and now it has been stuck in service for four days. The shutdown logs I submitted through Samsung Members are more than enough to justify a replacement. My device is still under warranty and I haven’t suffered financial loss, but this entire process has caused significant distress and worn me down psychologically. I want Samsung to stand behind the product and fulfill my replacement request as soon as possible.