I bought the computer with Windows 8.1 Pro. I requested and then upgraded to Windows 10 Pro. I began having 'error 1962: OS not found,,,' intermittently. The drive is a 2tb Seagate drive. There are 6 partitions on the drive from Lenovo and Windows is #4.
I cloned the C: partition into a new Seagate 3tb drive. That left me with 2tb + the leftover unallocated. I combined the two pieces in disk management to make one large partition with only the C: partition from the old drive.
It is not bootable. I get error 1962: OS not found when I try to boot from it. The drive appears to be locked. I used cmd.exe as administrator and ran diskpart and volume commands and the drive is not read-only or otherwise restricted. I have tried Bootsect and Bootrec with /fixmbr; /fixboot; /rebuildBCD commands but no success. I suspect it is because the big drive is GPT instead of MBR.
I have the Win 10 upgrade on DVD and tried refresh but it says the drive is locked. I have done the boot diagnosis but it tries to fix it without telling you what it is doing and in any case it does not fix it.
I think my problems are based in trying to get away from the extra partitions that are no good anymore and also that I am using GPT instead of MBR. I think the old bootmgr is looking for partition 4 and I am unable to change it's mind.
If anyone has an idea I would like to hear it.