TC reported TIMS shows Rear DT car, B2 door operation time out with an OPE status. Staff(BGB) onboar d the train. Checked and confirmed RDT B2 door cannot open. ~~~~~ Tims shown door open operation time out and #3669 B2 door was isolated and train resume service. Fault clear when door close command was given. Door close s/w were in closed position. Door lock s/w was interchange between unlock and lock status throughout the time of fault. C/O DLS and function test ok. Remove both door check roller found big roller give way from the bearing. C/O and push/pull testing ok. Door mating strip within criteria. Door cyclic 50x ok. Door static test ok. DLS UNIT-Old s/n: C151BDL161110.  New s/n: C151BDL194002. Not: 2263461 raised. Done by Koh/Sanip. 03/04/21.