at first thought i would check the rotors/brake discs and the pads for contamanant like greae or oil that a non thinking mech may have left some oil hand prints on the disc from the refitting process as these would have been removed on the fitting of the new clutch and so handled .clean the discs with a recommended clesner not oil based and if necessary as i belive it would renew the pads especially attend the right hand side as this i would suspect after this and ill fitting caliper or sensor or damaged or warped disc or bad bearing .all these can have a hand in whats happening before you have to interrogate the abs unit itself which is a job for professionals only.s