Win 10 no boot

[gen1]

OK, I have 2 hdd that have win 7 and my main drive that I use the most win 10

I disconnected all my drives and added an ssd. I installed win 10 on this drive. I then connected the other drives back up including the hdd with win 10 on.
When I booted up and checked the boot order, I noticed the new ssd had 2 partitions, even though i only installed win 10 on the whole drive. It showed an uefi boot manager and the under that the ssd win 10 on.
Followed by the win 7 drives.
All the win 7 drives booted fine as they did before. I thought I would check the original win 10 drive on hdd. It suddenly would not boot anymore!
I disconnected all drives including the new ssd, reconnecting only the original win 10 hdd.
Still no boot

It seems the win 10 install (which I made with all drives disconnected onto the ssd) has somehow corrupted the original win 10 hdd. I noticed on my install usb it had also created an eufi partition. Why has it done this??
I have no idea why and I really need to be able to boot my old win 10 hdd.

Any help much appreciated.

[PeterOz]

I have no idea why and I really need to be able to boot my old win 10 hdd.

Step 1
Connect only this drive
use the windows creation tool to repair the boot.
The repair option is at the install screen.

[gen1]

Already tried that , and also tried the fix mbr trick as well. I have noticed this drive seems to be gpt where the others are mbr. So I think this may be some of the problem, but it was booting before.

[PeterOz]

gpt is fine
any errors with the repair?

[Bruce]

@gen1 - still need help?

[Rustys]

abandoned closed