dope-rbs13

Hey guys just needing some help before I start pulling out wrong parts lol the brake pedal in my sil went real hard and brakes seem to have no effect (not that they are great in the first place) even pumping brakes has no effect. When the engine is off I can continuesly pump the brake pedal without the travel decreasing wheras a normal car u can only pump a few times before the pedal goes to hard.

Does this sound like a bad brake booster? Mc is fine, iv checked hose and one way valve going from plenum to booster and checked for leaking fluid etc...

Any help would be appreciated