Connecting another hard drive broke the boot record?

[mustacheman8]

I have a Windows 10 machine running on an SSD. In an attempt to move files from an old computer (windows 7), I connected the old HDD to my win10 machine.

After the bios screen, I was greeted with this: http://www.prime-expert.com/articles/b16/images/boot_error_status_0xC000000E.png
...which is a Windows 7 boot manager page. I disconnected the old HDD and restarted, only to arrive at the same screen.

Checked the bios, manually selected the SSD, but the same screen appears. I just ran a windows repair USB, but it only gives me options to fix the drive as if it was win7.

Has my SSD's MBR been rewritten with a win7 MBR? But that doesn't make sense.
What gives?

 

[Colif]

I deleted my first answer as I didn't see you had d/c the hdd and still got message...

What motherboard do you have?

Do you have a win 10 installer? On another PC, download the Windows 10 media creation tool and use it to make a win 10 installer on USB

Change boot order so USB first, hdd second
boot from installer, on 2nd screen after languages, choose repair this pc, not install
follow this until they talk about rescue discs: http://www.thewindowsclub.com/repair-master-boot-record-mbr-windows

What boot method have you got set in bios? If its set to UEFI/Legacy it might have looked at MBR on win 7 drive but I don't understand why its showing it still if PC booting off SSD. Try booting SSD again without hdd attached. Disconnect power from PC for a while and try again. Setting boot method to UEFI should have it ignore HDD completely and boot as normal off SSD.

 

[mustacheman8]

I tried a repair USB. Doing a bootrec /RebuildBcd resulted in the message: total windows installations: 0

I've got bios set to uefi, and the drive is visible and recognized as an SSD.

Motherboard is a asrock z77 extreme6 lga1155

 

[Colif]

I don't know how plugging the old hdd in did this to the drive. That "Win 7" boot manager might be win 10 instead, it sure looks the same: Win 10 boot manager

The message its giving is an inaccessible drive, I know of two fixes for it.

Two ways to fix this
1. open command prompt and type chkdsk /f and press enter. Might take a while. http://www.toppctech.com/inaccessible-boot-device-error-fixed/
2. The more common way to fix it is fresh install
If there anything on hdd you want to save? Try this: http://www.howtogeek.com/howto/windows-vista/use-ubuntu-live-cd-to-backup-files-from-your-dead-windows-computer/
Once you copy everything off you want to keep, follow this: http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html

clean install may want to wipe hdd so make sure to copy everything off you want to keep

 

[mustacheman8]

Thank you Colif, for your help.

I left out a detail up above. My system actually does have a storage drive. When I started the system with my SSD disconnected, (and to clarify the old HDD was also disconnected), but with my storage drive still connected, I got this windows boot manager screen:
http://techgage.com/wp-content/uploads/2015/11/A-Broken-Bootloader-In-Windows-10-680x510.png
.. which indicated to me that at least that drive still thought it was win10 (it does have some program files and user data on it).
Anytime I tried starting the system with the system drive (the SSD), regardless of whether or not the storage drive was connected, I would get this boot manager screen:
http://www.prime-expert.com/articles/b16/images/boot_error_status_0xC000000E.png
.. which is a win7 screen.

so, no one would ever believe this, but this is how my problem was resolved:
I got the bright idea to start the repair USB while having only my storage drive connected, so that the repair USB gave me options to try a Windows 10 repair (in an earlier post I noted that the system drive (the SSD) seemed to be stuck thinking it was win7...). I then connected the system drive (the SSD) to the system, and attempted a win10 repair. I was told something like, "couldn't repair your pc," and I restarted. HOWEVER, the computer is back up and running in win10!

This has been a really confusing experience, and I doubt anyone else has encountered this exact issue, but I hope this helps someone in the future.