I agree, but 2 possible issues
Bad connection on drive to mother board
Faulty cmos
But as all tests are fine now just not sure
I tried the boot repair disk tools and it found nothing to repair, mysteriously
Strange one. Any idea how this occured?
No idea, system reinstalled and no further reports of a fault, everything running ok
Just one of those things, or user playing where he should not be.
But unless he comes back case closed
It was most probably jinxed, which could be either removed by a lot of fiddling with it, or say some un-jinxing magic words over it.
As you arenât a wizard, you had to go the âfiddlingâ way of course 
I prefer to think of myself as a technical expertâŚ
I was going to say I am a doctor trust meâŚ
Or I use god mode but did not want to offend any one.
Better stick with fiddling till it works!