When you run it manually, that process should be dead, it just means it completed successfully. Basically there's a watchdog that only gives the viewgpu command a few seconds to complete (otherwise a stuck viewgpu command will make the script just wait for it to finish indefinitely, but if viewgpu runs normally, when kill goes to kill the process, it will have already terminated successfully).

If you weren't able to SSH in, it's possible that the Kernel just blew up? At that point, nothing will help you, not even Linux magic keys. You'll have to power button if the kernel explodes.

If you ever see a situation where it doesn't reboot and a card is dead (and you can still actually interact with the system) run the viewgpu command and give the output back.

But yeah, a malfunctioning Linux kernel, whether it's a kernel panic or some other kernel explosion means that your only likely resolution is actually powering it off.