Thunderbolt and mini Display don't play

Hello everybody !

i'm experiencing something we hate : the PBn'P plugitbutdontplay

Connected a 24" Apple Cinema Display (late 2008) to a Mac mini (mid 2011),

So miniDisplay to Thunderbolt

Display was flickering every 30s

went on www and found the 24-inch LED Cinema Display Firmware Update

Downloaded it, installed it, unplugged the Display for 15s

Flickers flickers flickers everywhere and black-out every 15s !!!!!!!!

Is there a way to uninstall this eye-damaging "Update" ?

Thanks