Using Radeon HD7770 and I get a Color Spinner After Installation

[nyrang]

Hi all, I followed this method and everything went super smooth until the first reboot after OS installation.
After boot, I'm presented with a solid cyan background, with a pointer that is soon replaced by the rainbow spinner. After a few seconds, the spinner disappears and nothing happens anymore.
Quick question: is it worth tinkering with boot options in this situation, since the system boots fine until then?
Also, I'm trying to install Sierra on a 40GB hdd, could that be the issue?

I have a Gygabyte Z77X-D3H mobo + i5-3550 and a Radeon HD7770.
Thank you for any help.

 

[Karelsky]

That is exactly the same problem for me cyan background, and i can't finish with the installation process..... Any help please! Thanks in advance....