This command enables or disables Emergency Management Services for the specified entry. bcdedit /bootems { ON | OFF } Specifies ...

This command enables or disables Emergency Management Services for the
specified entry.

bcdedit /bootems [] { ON | OFF }

        Specifies the identifier of the entry to be modified. Although this
            command will work for any entry, it is only effective for boot
            applications.

Example:

The following command enables Emergency Management Services for the boot
manager:

    bcdedit /bootems {bootmgr} ON