Spontaneous

Hi all, car was left parked for about 7 weeks and when i came to start it, it wouldnt do anything. Asked a mechanic to come change the battery when he finishes work and he did do. But now whenever i operate the indicators they click faster than they should even though all 6 bulbs are working. If i operate the hazard lights, they function as normal. Also, i cant lock my car via the fob, it just flashes and the interior light slowly dies out. I cant use the central locking via the button inside neither. Am i right in assuming i need to reset the bsi?? Also, is it best to stay in the car when taking the battery leads off and does just the positive wire need to come off or both. Any help would be appreciated.