Train stopped with stuck brake indication at Front DT car after departing SBW1. STBS operated. Pax d isembarked at ADM1. ~~~~~ Downloaded ER on PTU006. From ER observed #3626 stuck brake, approx 2.50 bar (EM BCP). Found #3626 ACU AC s/v is mod 3. Replaced ACU for #3626. Carried out brakes cyclic/function test ok. ACU-Old s/n: 1457-027.  New s/n: 1528-060. Not: 2166095 raised to RSW. Done by Kumar/Jack/Sateesh/Koh. 03/06/20.