I inadvertently exported Win System Registry file to a non system 32 ex HD

The system will not boot to Windows. On power up there is a black window counting down seconds, at zero the system powers completely off.

This is a custom made PC, a 8.1 upgrade to Windows 10. I cannot access the bios at all, no F keys work.

Will I be able to recovery with a boot disk or USB? Reinstall Windows?