Can it be that you did not used the latest image from RoPieee’s webpage?
Not that it shouldn’t work, but you’re using a Pi 4 and for that some stuff has changed.
Anyways, before we come to the “let’s reflash” conclusion first to the following:
Go into the webpage and press ‘commit changes’ and after that ‘save’.
No need to change anything, but this action triggers a re configure. There is a chance that it will recover from that with a working screen.