I have a 2010 Mazda speed 3, this year and model has a common problem with its amp.
Amp: Bose (BBM4 66 A20)
As soon as the car door opens, the speakers blast this machine gun sound and its because of the faulty amp.
I have opened up the amp and there is visually nothing obviously wrong, how can I further troubleshoot this problem (use of a multimeter?)? And is there something specific I should be looking out for?