hey guys.. not familiar with BMW forums for bikes.. can anyone suggest one? unless u can answer my question.. would appreciate it.

visiting the folks in montreal.. my dad has a K1 motorcycle.. last year he had his rear brakes changed, and upon arriving home he noticed that his abs light is on. Now that i am visiting .. here are the symptoms:
- abs light flashes on and off
- can hear the relay clicking on and off
- when you press the ABS switch, the click stops altogether
- since having the work done, the battery now drains completely within a week of the bike not being ridden

i suspect the abs sensor was maybe damaged or something.. but i only know jap bikes. can anyone suggest a solution, shed some light, or point me towards an online forum where i might find the answer?