Apple Screen won't work

Hi there, how are you?

I was gifted an Apple Watch series 6 three days ago.

Yesterday, the screen on the watch stopped working. It just remains blank.

I have tried charging it, disconnecting it from my iphone and pressing the two buttons on the side in various combinations.

Nothing is working, the watch screen remains dark.

A pop-up option occasionally appears on my iphone to pair with watch but when I open the prompt, it requires the screen to be scanned (and the screen remains black) or it requires a code from the device (and again the screen remains blank).

I brought it into a reseller in Dublin City Centre and was told they could not repair it in the shop and that it would have to be sent away.

Can you please advise the best way to get the watch repaired?