Hi Μαρία-Άννα,
Thanks for reaching out. I understand how frustrating it can be when a repair install fails with error 0x8007010a. This error often relates to update components or system integrity. I'm here to help!
First, make sure your device meets all Windows 11 requirements by running the PC Health Check tool. Compatibility issues can sometimes trigger this error.
Second, clear the Windows Update cache. Stop the update services, then rename or delete the SoftwareDistribution and catroot2 folders. Restart the services afterward this removes any corrupted update files that might be causing the failure.
Third, repair your system files. Open Command Prompt and run:
DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow
Next, remove any third-party antivirus, VPN, or shell mods, and update drivers.
Lastly, if the error persists, perform an in-place upgrade using the official Windows 11 ISO or Installation Assistant.
I hope you find this information helpful. Please let me know if you have any further questions If the answer is helpful, please click "Accept Answer".
Regards,
Carlo