Ubuntu – Lenovo G500 how to turn off secure boot to install Ubuntu 14.04

Follow the steps detailed on this page:

Screen brightness reset to minimum after every reboot

The file /etc/rc.local add before line exit 0:

echo 5 > /sys/class/backlight/acpi_video0/brightness exit 0

Where 5 is the brightness level from 0 to 10

The max brightness is defined in /sys/class/backlight/acpi_video0/max_brightness. The default is 15 on my laptop. So if you want to set it to 50%, you should use echo 7. – amazingjxq Dec 3 '11 at 3:50

In my Lenovo G500, max brightness seemed to be 100, so I added that line with 'echo 500'. Rebooted and no problem.

So I just now was able to successfully make my laptop a dual boot.

The way I got rid of the grub rescue prompt was actually by changing my boot mode from Legacy Mode to UEFI. I did this by booting into the bios menu when I turned on my computer by pressing f2 (for me). I then scrolled over to Boot and switched this under the Boot Mode option.

This got rid of the grub rescue screen upon powering up my machine. When I turned it on, it took me straight into Windows with no option to choose Ubuntu. My next step was to disable secure boot (see http://technet.microsoft.com/en-us/library/dn481258.aspx for more info on this).

NOTE: the disable secure boot option does not appear until after you switch to UEFI. I was now able to turn Secure Boot Off. The way to do this was also on the BIOS menu. I simply scrolled left to the Security tab (NOTICE: you should see an option for Secure Boot on the Bottom. You need not disable this, since my next instruction will disable it). I scrolled all the way down to Reset to Setup Mode and pressed enter. This Clears PK, disables Secure Boot (see for yourself on that screen) and enters Setup Mode. On a side note: I tried simply disabling Secure boot many times, saving it each time but this did not change anything when I restarted my computer (still booted to Windows automatically).

After this, when I rebooted I had the option to choose Ubuntu or Windows (since Ubuntu was already installed).

I did this on a Lenovo P400. My understanding is that this whole UEFI thing is unique to new operating systems, including but not limited to Windows (8 and 8.1)