The master cylinder is probably trashed. Changing the type of fluid without all-new parts was a mistake, as I doubt the older natural-rubber MC cups will work with the silicone-based fluid. Rebuild or replace the cylinders, or at least the master cylinder, if the others were redone rcently. Flush the system with alcohol, or pump a couple of quarts of DOT 3 fluid through the system to get rid of the DOT 5 stuff.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!