How to fix endlessly repeating Windows restore?

Question

Windows

The computer stopped turning on. They took it to DNS, and after returning the computer home, a new problem was discovered. Windows tries to recover every time it is turned on. There are no significant problems with the system itself, because. Through Ubuntu Windows starts fine. In the service center, they simply reset the BIOS, what to do now xs.

Answer 1

Windows starts fine with Ubuntu

What does it mean?
Using a bootable flash drive with a live system (you can take this one for example: https://adminpe.ru), test the computer: memory, disk, load testing.
If everything is fine, reinstall Windows from the correct Microsoft distribution.

Answer 2

First you need to carry the iron to the service and swear, it's not normal when after the service you are given unfinished work.
First, make a backup of critical data from ubuntu, I usually make an additional copy of c:\ProgramData and c:\Users, and maybe c:\windows\system32\config, so that I can restore the settings for applications if it is critical, plus there documents are usually stored.
Then, if the system was not installed by you, but it came with hardware, you need to use the standard factory reset tools, usually this uses either a hidden partition or an external drive or usb, the image of which can be downloaded from the manufacturer's website for your specific model).
If you installed the system (and solved the problem with the license yourself), then reinstall it and don't fool around.
Successful solutions to system problems on windows can be counted on one hand (this does not mean that it is not impossible, but it is easier to reinstall everything from scratch than to look for which system files are damaged, how to restore them, etc.)