Deep dive video on a custom build not booting due to bootmgr not found error. Below are some time stamps to key locations for 'quick fixes' but if you don't know what you're doing, it's important to understand the reason for this fault as well as knowing how to resolve it.
8:50 - Backup with with Drive Snapshot
32:15 - The Quick Fixes
37:16 - Vanilla Install, Restore Win Partition Only method
