The laptop is Sony Vaio SVF1521B4E.
I have repaired it by changing the original defective motherboard (i5-3337U) with a cheaper version (Pentium 987).
The laptop boots and works normally from an extern USB with Win 8.1 live OS.
The laptop is stuck when I boot from original SSD with Win8.1.
No matter what repairing method I have tried, it says cannot repair Win 8.1.
I do no want to install Win 8.1 from scratch, because I need some programs/settings from existing Win 8.1 installation.
I do not have a previous saved session to returns/recover from that point.
I would prefer a kind of install repair, but everything what I have tried it does not work, it says always is a failure and cannot repair Windows.
Maybe it has to something to do with some settings/drivers related with previous motherboard or the boot (GPT) partition or I do not know, but I would like to avoid clean re-install of the Windows.
What suggestions do you have?