I have two virtually identical machines (1 & 2) running Leap 15.3, which I keep updated, usually in parallel by running zypper up.

Today I started an update on machine 1 which required a re-boot, so did that and then switched to machine 2 (I use KVM, the machines are remote) and started the update on the second machine.
While waiting for machine 2 to update I returned to the first machine and found that the machine had re-booted but the screen was still dark and had gone to sleep.

I made the trip to the machines and found machine 1 running normally with no warning lights but I couldn't access it as I had no screen. I had to power cycle to restart.
The restart repeated the problem; no video, so I rebooted again and reverted from the grub start, to an earlier boot which started normally and now I have my screen back on machine 1.

On machine 2 the updating process has completed but I have not re-booted for fear of the same problem.

Where should I start looking into the upgrades which have been installed on machine 2 but not yet rebooted to identify the problem with the video.

Because I have not yet rebooted machine 2 and have reverted on machine 1, both according to Kinfocentre are at
Kernel Version 5.3.18-59.4-default.

The update has the following line for the update which failed:-
[CODE]( 5/58) Installing: kernel-default-extra-5.3.18-150300.59.43.1.x86_64 ...................[done]

Other than the kernel where should I look to identify the problem.
Should I risk re-booting machine 2 to see what happens?