Can you post the output of
curl -sSL https://raw.githubusercontent.com/pimoroni/hyperpixel4/master/hyperpixel4-debug.sh | bash
And do you have a hyperpixel4.dtbo in /boot/overlays?
BTW are you using a RPi 4? There are a lot of issues on github with RPI 4s and black screens.
Edit:
It’s a bug since bullseye, see https://github.com/pimoroni/hyperpixel4/issues/155
Some solutions were this https://github.com/pimoroni/hyperpixel4/issues/155#issuecomment-966455983
or to use dtoverlay=vc4-kms-v3d instead of dtoverlay=vc4-fkms-v3d in the config.txt
Good luck.