I recently installed Ubuntu on dual-boot mode with pre-installed Windows 8.1. When I turn on my laptop, it boots straight to Windows without showing boot option or GRUB. However, I can boot to Ubuntu by doing, in windows, an Advanced Restart --> Boot from device, and I can see Ubuntu here. By doing this I can get into GRUB and boot into Ubuntu without any problem. I have tried all the ways I could find on the Internet and failed. Asking a question is my last resort, so I really hope someone could help.
P.S. I tried doing boot repair and this is the URL to pastebin: http://paste.ubuntu.com/10744176/