USB Mouse not working with LED On, a very rare problem!

Bought a Lenovo G-50-70 laptop (http://www.flipkart.com/lenovo-g50-...1,,,c,,,,,,,&gclid=CPGl-o3shMYCFQoIvAodskkAXQ)

Facing an issue of zero response to USB mouse connection in any of the USB slots.

Points -
*Pen Drives are working fine.
*Mouse LED is on when connected but doesnt work.
*All drivers installed properly.
*Every device is working properly (checked from device manager).

Have Windows 8.1 Pro installed. Thing is a lot of blogs say, I need to disable the 'Intel XHCI' to ensure USB mouse or Keyboard works.

Now the problem is, HP, Lenovo or Sony in generic, comes with Insyde20 UEFI BIOS (unlike ASUS, which uses Gigabyte UEFI BIOS which doesn't hide features of BIOS), where they purposefully hide 'Advanced' or features of that sort for users to not unknowingly mess with the system.

Now to bring 'Advanced' tab back in UEFI BIOS, I need to do a BIOS Modding in this way - (donovan6000's Blog: Insyde Bios Modding: Advanced and Power Tabs), which is a tiresome process, with an added chance of semi bricking the system.

Is there anyways other than this to enable usability of USB Mouse/Keyboard?

The Lenovo care's senior technicians don't have any solution to it, and hence is asking to format from 8.1 Pro to 8.1 Single Language User. LOL

Please Help!