Iphone 14 pro seems not to react any more...

Just got the new iphone 14 pro....

I have made the quick transfer from my iphone 13 pro to the iphone 14 pro.

Followed all steps as usual with enough battery power and new phone on the power connection.

After all initial steps both iphones said transfer of all details takes about 45-60 mins.

After coming back, old iphone 13 pro says transfer complete.

New iphone 14 pro has a black screen and us un-responsive.

Pressing and holding the start button doesn't do anything

What can I do??

Thank you

Kind regards

HGJA