ubuntu – Laptop not entering dual boot menu after crash of one OS

I was running Ubuntu 21.04 on my Lenovo T480 Thinkpad, and the device froze. After pressing the power button to reboot, it started to the normal Lenovo splash screen, and offered the bios menu. The bios menu option disappears after five seconds.Typically it would progress to a a dual boot screen then, where I can choose to boot Ubuntu or Windows, but now the computer stays on the splash screen until I reset it by pressing the power button.

I can bypass the dual boot menu by launching windows via the bios menu, but if I attempt to launch Ubuntu using this same method, the computer screen stays black until it’s reset by the power button. None of the function keys have any effect

Since then, I’ve applied a firmware update, performed system checks in the bios menu, and removed my laptop batteries and performed a power drain, but none of those worked. Does anyone have advice on other strategies I could use to try to get things working? I would appreciate any help