All train doors proven closed with DIR illuminated. Opened and cliosed train doors to no avail. TC c onfirmed both cab doors were proven closed. Pax were disemba rked. ERS-10 ~~~~~ 3501 All train doors proven closed with DIR illuminated. Opened and closed train doors to no avail. TC confirmed both cab doors were proven closed. Pax were disembarked. (Level 3) L3 501/502 ER D/L. Replaced 3501 COR-6 & DIR-1/2/3 relays. All doors sensing s/w & plunger checked - OK. All door guides checked/found no FOD.  Kwa ZY 44621