chromebook problem

[digimark]

Hi guys

Just installed ubuntu on my new chromebook acer c7. Installation went great. Installed my apps etc.

Used
Sudo cgpt add -i 6 -P 5 -S 1 /dev/sda

To set up default ubuntu boot but to no avail. It keeps going directly into chromos

It's in dev mode all screens are as they should be but I can't now get it into ubuntu......

Please help.

Thanks