Solved! Go to Solution.
First try the colour panels test via opening in your phone dialer app and dial *#0*# and look for the colour panels and switch through them a few times to see if this jolts the pixels back into life.
If not then a Samsung Experience Store or Samsung Service Centre can help and or if you was supplied the phone by a Network ask them for a replacement.
I wish you all the best with this.
Current Phone > Samsung Z Fold³ 5G.