I was using grub to dual boot my Lenovo Y410P with Windows 8 and Ubuntu 14.04.
Recently I finally decided to upgrade my Windows 8 to Windows 8.1 considering it should be pretty stable by now. However, to my horror(or rather not surprisingly), my default bootloader has been changed to Windows Bootloader which means I could not access my Ubuntu 14.04.
Usually this takes a while to fix, involving repairing grub/BCD and tend to be tedious. However, I managed to found a much simpler and direct solution to this.
With the new UEFI specification, we can actually choose the default boot manager instead of replacing one with another. All it takes is to go to UEFI Firmware settings and change the order of boot managers. Which means grub and Windows boot manager can co-exist somewhere in the hard disk and we can choose which one to use in the BIOS UEFI settings.
Accessing UEFI settings in Windows 8.1 is a bit different from what happens in Windows 8, you can follow these links:
Today I booted to my Ubuntu but it welcomed me with a blank screen without any light from the screen.
I thought it is the normal brightness and back-light problem so I tried to turn up brightness level from keyboard but nothing happened.
Then when I tried to adjust volume using keyboard, I was surprised(or rather not surprised) to hear the usual sound effect from Ubuntu system. So I was assured that the system has been booted properly and the only problem is that the screen did not show up.
Intuitively, I thought of the possibility that the screen is actually “turned off” the same way as the brightness was set to zero on boot. With that I tried to press the keyboard combination to “turn on” the screen, which is “Fn+F2” (for my Lenovo Y410P).
And yes, I got back my Ubuntu desktop. Pressing the keys again will give me blank screen again(as expected since it is indeed designed to work).
No idea why the screen was initially turned off though.