Dell Precision 5820 USB-C Ubuntu 18.04 can't install blank screen

We 're trying to install ubuntu 18.04 on Dell Precsion 5820 USB-C type model after the install splash screen it goes to blank screen . we added below directives

In the grub "Install Ubuntu" prompt.

( Press 'e' ) Remove "quiet splash"

Add "nomodeset acpi=off"

Then hit "Ctrl + x "

Still no luck. Please let me know how to proceed from here. We already tried keeping acpi / nomodeset alone. Still no luck

Ubuntu 20.04 LTS no issues, it loaded smoothly.

In our environment, we having old versions of 5820 which worked before acpi/nomodeset