park brake fault system not functional?

hey guys,ive got a 2005 range rover sport,and i engaged the electronic handbrake,as normal when i was parking.then 10 minutes later.I got back to the car and started it,released the handbrake,but it didnt respond,a warning light came up,saying park brake fault system not functional.so i decided to switch the car off.get out and close all door.gave it 15mins,for it to re-boot.but same problem.I couldnt move the car.got stuck for 3 hours waiting for recovery.anybody knows what caused this?and how to release it manually?why did this happen?is this a common thing for range rover?Thanks