The problem I have, is other than your saying you tried "sax2" and my "fast" answer did not fix your problem, I do not know what specific sax2 commands you tried, so I have no means of suggesting you try something different.

If I can illustrate what I mean by a question, did you try:
sax2
sax2 -r -m 0=vesa [reset graphics and try vesa driver]
sax2 -r [reset graphics to default intel]
ssax2 -r -m 0=i810 [reset and try the alternative driver]

I know that you may have tried all of the above is very obvious to you (because you did the typing), but as a user reading this, trying to help, I am mostly in the dark. Your general descriptions are good for an over view, but not too helpful for specifics.

Edit: also note you should do these changes from run level 3. ie. boot the PC to run level 3 (by typing 3 in the grub boot menu options line). If you try them from runlevel 5 they won't work.