Вариант с bootsect.exe Запускаем ее с ключиком /help получаем

bootsect {/help|/nt60|/nt52} {SYS|ALL|:} [/force] [/mbr]
Boot sector restoration tool
Bootsect.exe updates the master boot code for hard disk partitions in order to
switch between BOOTMGR and NTLDR. You can use this tool to restore the boot
sector on your computer.
/help Displays these usage instructions.
/nt52 Applies the master boot code that is compatible with NTLDR to SYS,
ALL, or . The operating system installed on SYS, ALL, or
must be older than Windows Vista.
/nt60 Applies the master boot code that is compatible with BOOTMGR to SYS,

ALL, or . The operating system installed on SYS, ALL, or
must be Windows Vista, Windows Server 2008 or later.
SYS Updates the master boot code on the system partition used to boot
Windows.
Updates the master boot code on the volume associated with this
drive letter. Boot code will not be updated if either 1)
is not associated with a volume or 2) is
associated with a volume not connected to an underlying disk
partition.
/mbr Updates the Master Boot Record without changing the partition table on
sector 0 of the disk that contains the partition specified by SYS, ALL,
or drive letter. When used with /nt52 option, the master boot record
is compatible with operating systems older than Windows Vista. When
used with the /nt60 option, the master boot record is compatible with
Windows Vista, Windows Server 2008 or later.
Example:
To apply the master boot code that is compatible with NTLDR to the volume
labeled E:, use the following command:
bootsect /nt52 E: