Testing px4 changes on pixhawk 2.4.8 hardware

Hi. I am trying to change a few lines of code in the pwm_out.cpp driver in the PX4 firmware which is responsible for assigning the PWM values (in microseconds) to the hardware pins (ESCs). My build and upload of this change is successful, however, there is no change whatsoever on the hardware. The motors spin just like before. Does anyone have a lead on how I can test the PX4 code changes on the PIXHAWK drone (hardware)? What am I missing?

Thanks in advance.