Train doors not proven closed at RDT A2door, unable to close. Pax were detrained. ~~~~~ 3634 A2 Train doors not proven closed. Unable to close. Pax were detrained. Level 3 (DIRBS operated) UPD L3 3634 TIMS showed 'CLE' on A2 door. Checked A2 door for any FOD, door guide & weather strip - OK. Door locking device checked/found no defects. Door able to be isolated. Performed door resistance test = 5.2 kgf. Cleaned J-rail as preventive measure. OPS 20 raised to follow-up.  Au TK 44403 To continue rectification. L3 3634 tested A2 door isolation v/v & release v/v - OK. Function test door operation - OK. Checked door plunger sensor s/w operation - OK. OPS 30 raised to follow-up.     Chan GF 44403 To follow up. L3 3634 replaced A2 door DCP. Function test door operation - OK. Viewed CCTV footage & found Station Staff apparently have FOD removed from guide rail.  Au TK 44404