Ok do one thing if you have a lap connect your device with data cable and swith of your device then press volume up and power button together when samsung logo appears release power button you will enter to system configuration from there press volum...
I think they gived you defective or **bleep** product can you plz check your device settings About phone > status information>phone status wheather its showing official or not.Am also using s25 ultra i didnt face any isssue like this.
