Hi
Are you saying that you can boot into Windows 10, but slowly as if something is interfering?
Once you are booted into W10 do things work, can you open and run software etc.?
If that's the case this is just what I'd try, I'm just going by past experience, if you can run stuff in Windows 10, I'd download and install EasyBCD because the graphical interface makes it a lot easier for me to understand what's going on.
If when you open it, you can see both your Windows 7 and Windows 10 operating systems, make sure Windows 10 is in position number 1, and set as the default OS.
Tell it you don't want to see a boot menu, and remove the Windows 7 option from the boot menu.
Say OK, and shut down and unplug the Widows 7 drive from the mother...