hello mini people

i have christmas tree dash with abs,traction control,dsc and brake sensor warning code.they showed up every time i stop the car with ignition off.when i restart car sometimes they stay on sometimes not.
ive SEASRCH a LOT info here and there but it seems reason can be couple

fault brake sensor,fault abs sensor,low brake fluid,bad battery, and worse abs module
my guess its fault abs sensor but scan tool doesnt show which sensor is bad it only throws dsc control unit supply with 5e2c code
i went to dealer they suck,bla bla bla and 600$ for diagnose the car

so can u guys tell how can i check abs module for malfunction?
or which scan tool i can use to be sure whats wrong with my car??

 

nobody??