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#21
"Bootmgr is missing" occurs when you try to boot a HD which doesn't have its boot files, as yours didn't.
When an installation will not appear to repair in Startup Repair, it may require the bootrec commands to force it. Steps 1-3 from Error 0xc0000225 on boot is the best presentation of them to see how they actually work in the Command Prompt. Steps 1-3 do not pertain at all to Linux.
The actual link How to use the Bootrec.exe tool in the Windows Recovery Environment to troubleshoot and repair startup issues in Windows does not show how to sequence or even phrase the individual commands.
No prob, I was trying to figure out if posting up Theog's demonstration of bootrec commands in the Command Prompt is too confusing or I should stick with the MS bootrec tutorial which doesn't sequence the commands.
Glad it's working for you now.