TC reported train doors at rear DT car did not opened. Staff(BGB) checked and confirmed rear DT car 'B2' door did not opened. Staff(MSL) later isolated the defe ctive train door in closed position. TC reported train doors ~~~~~ 3616 - TC reported train doors at rear(3615) DT car did not opened.Staff(BGB) checked and confirmed rear DT car (3615)'B2' door did not opened. Staff(MSL) later isolated the defective train door in closed position.  3615 b2 door check and found both door roller was damaged, Replaced both door roller and function check ok, Door cyclic test and door static test ok done by Yusof/Haikel 45169