TC reported "open door " command was available but train doors was unable to open. TC performed plat form duty to open train doors. ~~~~~ TC reported "open door " command was ava     LDC logs shows D.O.M @ manual no DOBRS/DOARS were request to open train doors.VOBC active @ EMU517.Remove console cover and check console DOS contact fail.DOSB2 no good causing OL.Replace DOSB2 limit s/w and function tested ok.Vertify door open report from VOBC-ok. Done by Kenneth  14/04/23