Looks like HP has released a bios update, please install. Then you can try to install a current kernel and firmware:
https://forums.developer.nvidia.com/t/ubuntu-18-04-cannot-boot-after-installing-recommended-nvidia-driver-470/211119/5?u=generix
Looks like HP has released a bios update, please install. Then you can try to install a current kernel and firmware:
https://forums.developer.nvidia.com/t/ubuntu-18-04-cannot-boot-after-installing-recommended-nvidia-driver-470/211119/5?u=generix