New Apple Watch Ultra won't turn on after charging and resetting

I just bought an Apple Watch Ultra new and opened it, but it won't turn on. I have tried charging it with a 5-watt magnetic USB cable and a 20-watt magnetic cable C for 3 hours alternately. The Apple logo appears for a few seconds, then the screen goes black. I have also tried resetting it by pressing the two buttons on the side for 30 seconds to 1 minute, but it still won't turn on.

Please help me.

[Re-Titled By Moderator]