I got the picture now. This is something that has never happened to me, as I maintain & protect my PC's well.
What has happened several times throughout the years, is having hard drives simply die. Salt air corrosion and power failures damage the mechanichal parts inside and one day they just can no longer turn, or if they do, they're just dragging and making noises. Regardless, at that point, they're just good for the garbage can, so partitioning would not be helpful for me at that point.
When I run into a situation, such as you describe above, I can usually get in by "safe mode" or using a "boot up" disc, or at the very least, reinstalling Windows over the old one, without formatting, so as to not lose all my programs & files.
My guess is that they didn't even need to change the motherboard, and after changing it and realizing it still didn't work, they reformatted the hard drive, because they were dumb as stumps.
Ken, if anything like this ever happens to you again, call me up or bring it over here, so I can look at it before you give it to the technician.
Regards, Marco.