Solved windows update stuck reverting changes. broken monitor.

i have a laptop windows 8.1 64 bit on it. it downloaded windows updates and got stuck when completing 100% saying it failed and started to revert changes. it got stuck for a whole day now. so i downloaded wind 8.1 iso with media creation tool and put it on a usb.

since it's monitor is broken and it's my friends laptop i took it home to fix it over night and return it to him tomorrow since he's addicted to it playing euro truck simulator 2.

however there's a problem. i got the windows boot menu where you can choose to repair or restore or do some cmd's.
they didnt work and said the hdd or OS was locked and i needed to unlock it then restart the pc and come back to the restore option. didnt know what to do so i restarted thinking it didnt recognize the os properly. didnt work after restart.

so i clicked on what i though was a reinstall while keeping your files. but i got a second glance at it and i think it said recovery while you lose your files. idk about steam and euro truck simulator 2 and cloud saving. som im afraid his save files are gone unless you guys know something i can do.

i booted up the usb since it fail to detect the hdd since i chose the recovery option i restarted thinking i didnt want him to lose any files.

chose language and clicked next, clicked repair this pc and opened cmd window.

now i can see in diskpart that the " disk 0 is 931 GB free 0 in list disk. all is healthy in list volume and there is a recovery, system, reserved, primary and recovery partitions.

in bios i can see the disk. but when i override boot selection it just tells me to insert boot device.

i can try first if you think it could work to rebuild the bootmgr. i just though of that since i think its one of the first things the recovery operation goes through when it does its thing.

but then i need to get past the windows update could not complete reverting changes.... i only have the range of the usb with the iso of win 8.1 which the laptop also has to work with.

ok now it can boot again. i did a bootrec /fixmbr. how do i get from here to recovery. i can try to see if the os is not locked now since it can boot up to the "We couldnt complete updates reverting" thing again.

oi fixed it. did the bootmgr thing then i googled and found that "power on your pc then immediately hold down ALT + F10 until it starts the recovery section and restore computer without losing any files" works.