Windows 8.1 failing to boot after BSOD

I've come across a pretty hefty problem. A couple of days ago, I was using my computer (Desktop) when I suddenly got a BSOD. My windows 8.1 boot then got stuck in an automatic-repair loop where it fail with this message: failure image.

I'm tri-booting with Windows 10, Ubuntu and Windows 8.1 so I get to grub2, can access the options between win8 & 10, then if I select win8, that's when it takes me to the auto-repair loop. I am able to boot into Windows 10 and Ubuntu thankfully so I can access my files.

Here is the output of SrtTrail.txt:

Startup Repair diagnosis and repair log

Number of repair attempts: 1

Session details

System Disk = DeviceHarddisk0 Windows directory = D:WINDOWS AutoChk Run = 0 Number of root causes = 1

Test Performed:

Name: Check for updates Result: Completed successfully. Error code = 0x0 Time taken = 0 ms

Test Performed:

Name: System disk test Result: Completed successfully. Error code = 0x0 Time taken = 0 ms

Test Performed:

Name: Disk failure diagnosis Result: Completed successfully. Error code = 0x0 Time taken = 500 ms

Test Performed:

Name: Disk metadata test Result: Completed successfully. Error code = 0x0 Time taken = 0 ms

Test Performed:

Name: Target OS test Result: Completed successfully. Error code = 0x0 Time taken = 47 ms

Test Performed:

Name: Volume content check Result: Completed successfully. Error code = 0x0 Time taken = 0 ms

Test Performed:

Name: Boot manager diagnosis Result: Completed successfully. Error code = 0x0 Time taken = 62 ms

Test Performed:

Name: System boot log diagnosis Result: Completed successfully. Error code = 0x0 Time taken = 0 ms

Root cause found:

Boot manager failed to find OS loader.

Repair action: File repair Result: Failed. Error code = 0xa Time taken = 5594 ms

Repair action: Boot configuration data store repair Result: Failed. Error code = 0x490 Time taken = 63 ms

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I've tried just about everything, using a repair disk doesn't fix anything and I'm unable to use the "refresh".

I've ran some disk checks and everything seems in order.

Something suspect I've noticed is a file "WindowsUpdate.txt" sat in D:Windows (my win 8 install) which is dated/timed to round abouts when the bsod occured.

Anybody got any ideas because I've got no idea what to do.