Windows 10: Not exactly the BSOD but Win10's startup is broken.

This issue is my friend's who has spent many hours building data using non-Microsoft apps. His laptop refuses to start up into Win10. Microsoft agent says the way forward is to do a custom install on the C: drive. There are three other drives that my friend has created on his 1TB HDD. He wants no risk of losing his data. The Startup auto repair cannot repair. I can get into CMD but I don't know any command lines that would help. I know basic dos.
Surely there's a work around since all...

Not exactly the BSOD but Win10's startup is broken.

 

Can't get GPU-Z to start with Windows 8.1 startup

I'm not sure how to do that. Could you list the steps for a noob?

 

Windows 10 - cannot add exec to Startup in Task Manager

I purchased a new computer with Windows 10 already installed. I am trying to add an exec to the startup list but Win10 will not accept it. The exec runs successfully on my Windows 10 machine if I start it manually.

Steps I've taken: Task Manager, Startup Tab, File>Run New Task. (browse to location, select.) It will start immediately, but does not show up on the list to autostart, nor does it start on reboot.

Any suggestions?

 

Nvlddmkm.sys BSOD on startup?

The problem is the laptop (specs in signature) not rig in system specs.

Sometimes when I switch it on, Vista loads normally.
Other times, just after the horizontal 'loading' bars and before the Vista orb appears, I get a BSOD of Nvlddmkm.sys or Nvlddmkm.dll then the laptop reboots, BSOD's, reboots... it can happen like 5 times!

I've been googling all morning but apparently there's no solution to this?

It does the BSOD only during startup. Once Vista loads, it never BSODs not even during a game.