Windows 8.1 recovery due to Windows 10 external hard drive usage?

Question

Iron

Good afternoon! Installed Windows 10 on an external hard drive. At the next boot, the disk scan on the external one accidentally passed. After that, problems arose: the main disk began to load from the third time. Booting once again from the main disk, a disk error popped up, asking me to reboot. After that, when you turn it on, "preparing automatic recovery" appears, and then a black screen. I waited about an hour, but the recovery does not happen.
Make a bootable flash drive? or are there other options? What could affect disk performance?
update. The system on the external hard drive is also corrupted and offers a factory reset.
Update/Solution. Windows 10 somehow "integrated" the Windows 8.1 drive into itself. Thus, when using the installation disk with Windows 8.1, when trying to roll back the system through a restore point, an error occurred due to the fact that no OS was selected for recovery. It was necessary to use the installation disk with Windows 10 and there, through recovery, select the required OS. Further through the restore point.
Thus, when using the system on an external hard drive (if there is also a main one), it is better to do the following:

1. Disable scanning on an external drive
   
2. Boot not through the boot menu, but each time manually setting the required disk in the BIOS
   

Answer 1

This is a typical boot recovery case. Here is the standard operand mode:
1. In BIOS Setup, in the boot priority list, put your system disk in first place (topmost).
2. Using Acronis DD (or another similar utility), check if your system disk partition is active (marked with a red flag). Unchecked - make it active, sometimes that's enough. True, there is a nuance here: if there is a hidden (system-reserved) FAT32 partition of 100 ... 300 MB on the same disk, and it is already active, leave it like that.
3. Run the computer from any LiveDVD/LiveUSB recovery tool containing the well-known 2k10 utility package, and select one of the boot recovery utilities in this package (there are about a dozen of them). Use it to restore the bootloader on the active partition.

Answer 2

Making a bootable flash drive and reinstalling Windows would be the easiest solution - https://www.youtube.com/watch?v=y8bvM5XNPoM

Answer 3

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