Login screen faliure

[marvstod]

On 2023 MacB00k Pro with M2 chip, Ubuntu Asahi variant has been fine for several months
Following reommended software update including a kernel , initial reboot to Asahi option is ok.
But instead of Logon Screen choices, there is only a grey screen.

Attempts to access prior kernel through any Advanced Menu failed.
Both right-SHIFT and ESC keys were attempted to bring up an Advanced/Grub menu, but without success.

Thus guidance is needed for accessing boot kernel uptions
Or is a Asahi reinstall unavoidable?

[marvstod]

Some additional detail.
The intiating U-boot ran, followed by secondary (right side displayed ) bootup scripts, but only a gray screen manifested. The ESC and right-SHIFT attempts to access a kernel choice Menu were done at a variety of times.