

Implying that the RECOVERY partition don't have an operating system...
It was the PBR (bootmgr) of the RECOVERY partition you wanted me to refresh isn't it ? or the one of the SYSTEM or Windows partition ?
That message usually indicates that the mbr executable executable code can't find an active marker in the partition table.
Try using bootice to
1. install mbr NT6 code,
2. double check you have a partition marked active
In the above sequence, all boot Fx keys (F2, F3, F8, F9, F10, F11, F12, ESC, DEL) are managed by who ? They usually are pressed before POST but it does not mean that it is the POST that treat them. The second in line is the MBR so, as hinted by Samuria, could it be that the MBR is the one that treats all Fx booting key calls ?BIOS/MBR boot process from hard disk goes like this:
- BIOS firmware initialization and self test (Power On Self Test - POST)
- load and execution of MBR (Master Boot Record) on first disk
- load and execution of partition boot record (PBR) on active partition
- load and execution of boot manager ("\bootmgr") from active partition and then display of boot menu (skipped if only one boot entry)
- load and execution of Windows NT6 loader - file "winload.exe" from \Windows\System32 folder
- load and execution of kernel and drivers
For a successful boot, at least to boot menu, following items are needed;
- Microsoft MBR (use bootsect.exe to fix Master Boot Record)
- Microsoft NT6 PBR on active partition (use bootsect.exe to fix Partition Boot Record called also VBR - Volume Boot Record)
- \bootmgr on active partition (or \EFI\Micosoft\Boot\bootmgfw.efi on ESP)
- \Boot\BCD on active partition (or \EFI\Microsoft\Boot\BCD on ESP)

'Physical disk | Process MBR' ?