After restarting, the monitor turned off during the startup

[vvgloo]

I did emerge world --exclude=gentoo-sources, then to restart computer.
After restarting, the monitor turned off during the startup.
I see that the character interface is starting, showing that the hard drive is scanning and mounting, and has not yet started to the location where the username is entered. Then the monitor lost signal.
I checked the hardware and it's fine. The other system on my computer is working properly. And it's still in the character interface, so it shouldn't have anything to do with X. I did not update kernel, so the kernel is old.
I am currently unable to access the system and am looking for a boot disk to check again. What should I check for this issue?
Thank you all first.

[sublogic]

Temporary workaround: if you use a bootloader and know how to change the kernel command line, try adding nomodeset .

Your framebuffer seems to work, but the final graphics driver seems to fail. The kernel option above will leave you in the framebuffer. It's not a solution, but you should be able to log in and investigate. For example, look at the dmesg output.

[vvgloo]

thanks
ssh can be connected fortunately.
I have tried add nomodeset in boot, but no difference.
I reinstall nvidia-drivers in all editions, it's not work either.

my dmesg: https://pastebin.com/1w8er1ar
I didn't find any useful information

[vvgloo]

Miraculously, I was able to log in and execute startx on a black screen by blind typing into X. The display worked. This glitch only occurs in the second half of the character screen, so what should I be checking for?
the dmesg:
nvidia: module license 'NVIDIA' taints kernel.[ 3.790000] Disabling lock debugging due to kernel taint
is this a key?

[Hu]

No, that is a standard error whenever you use closed source drivers, due to their historical reliability reputation.