Finnbarr has a new blog post, on diagnosing UEFI-centric issues with modern Windows systems, with lots of figures and screenshots and background information:
[…] I hope this detailed explanation of how Windows 10 boots on a UEFI-platform will help you keep your sanity the next time you boot and see a missing or corrupt BCD message. Remember to always configure your platform so that you can boot into a UEFI shell using the UEFI firmware-based boot manager and make a backup of your BCD store.