Try booting with the HDD disconnected. Try disconnecting the battery and BIOS battery (where is it on this model?!) for a few minutes.

You would still need good RAM to get into the BIOS update…

GPU failure, since a text-mode boots but not much else?

No problem. I think in my case only Wine/Proton games were doing it and native Linux games were fine. I shake my fist at Nvidia and carry on. 😂

Try this setting: Display Configuration > Screen tearing: Allow in fullscreen windows. Whatever it’s set to, try the other setting. I had a similar issue once and this fixed it. The issue came back a long time later and switching it again fixed it. 🤷‍♂️

It’s a difficult issue to pin down. I’ve also read about video stuttering while trying to stay synched to pipewire audio which is having buffer underruns, even if your audio sounds fine. To check the audio buffer, you install and run pw-top and then watch it while you are having the video problem.