When it says it is looking for ntldr, it is looking at the MBR of a drive and expecting to find an XP type bootloader. Since Bootmgr has been used since Vista, possibly the bios is not seeing the correct drive.
If you cannot access the Bios or some type of Boot device menu to adjust the system to boot to a Windows Boot Manager, I suppose you are stuck... I have been unable to tell if such a situation is caused by the OEM boot setting utility being overwritten or something else. But try hitting the keys and do it very, very early in the boot scenario and keep tapping.
It is basically impossible for us to tell the exact situation, but if you could boot to any install media, it might give you some options. I don't think you are the only one recently to have this exact same situation.