1999 Volvo S80 "brake failure stop safely wont" Questions

...to change from parking to drive or reverse it get stock it wont move. It has a messege brake failure stop safely asap. I need help to know what it is. I already took to shop nd they didn't fix ...

...BRAKE PEDAL FOR TEN SECONDS. NOW YOU CAN TURN THE VEHICLE ON. THAT SHOULD TAKE IT OUT OF SAFE MODE Make Sure The Problem is Real First I have a 2002 X5 and get this message ("Trans.Fail Safe Prog.") ...