Mac issue

[DeSynthed]

Sorry but i need help. I have been using Technic launcher for a while Voltz Specifically, recently when I log in FML does whatever it has to do then all the sudden a checkerboard flashing screen, this occurs on any modpack,

Troubleshooting I've done:

-Deleating my technic folder.

-Re downloading the launcher

-adding other packs

-check java for 64bit

-use the download files for the vanilla launcher

Interesting fact,

-prior to the voltz update i manually was playing voltz through the vanilla launcher (since the update I can't get the correct filles swapped in)

- It seems that not all the files are downloading (due to the fact that it doesn't work in vanilla mc launcher)

THIS IS A MAC THAT I AM USING not a PC. and please I need help.