2002 Chevy Blazer wiring

Electrical problem
2002 Chevy Blazer Engine Size unknown Four Wheel Drive Automatic 61000 miles

I recently had the ignition cylinder replaced. Since that time, I have no right turn signal (the bulb and flashers work). Also, the alarm will go off sometimes when not set. If the car is off, depressing the brakes turns on the headlights and radio. If the car is running and I depress the brakes, turn off the ignition and take out the keys, the car remains running and the headlights and radio stay on. Could the mechanics who replaced the ignition cylinder have created shorts or destroyed the wiring?