UnderVolted Notebook CPU too much, now just keeps on loading the windows logo after soft reboot

[H.K.]

Asus X550LN 

Cpu : i5 4200u

GPU : GT 840m

RAM : 8 GB 

Used for long gaming sessions from 2014,

after 30 mins of performance use temp goes to 90° +

So my notebook CPU has been throttling for over a couple of years now and thought might undervolt just a little so that the temp might go down and can use it for long sessions of browsing and videos. 
Used intel XTU to go under -.05 V and was doing fine, but then Stupidly jumped it to -.1 V without thinking, PC rebooted instantly and got stuck doing the windows logo loading, as shown in the photo.

Can used the X drive cmd from boot troubleshooting but can't reset windows.
And I need the files on the C drives as well. 

Can I reset the voltage anyway without installing a fresh windows, is it possible at all?

[Electronics Wizardy]

safe mode? restore backups?

[owencrispy]

or take it apart and reset the cmos? clears overclocks as well as undevolts i think