Definitely aftermarket, that's a Kicker 4 channel amp
I'm going to go with that cylinder being a fan. Reason being is that it's installed under the rear hatch carpet and the previous owner was making an attempt to keep the amp cool. Plus I can see a relay that is wired to come on with the stereo and draw power from the big red power wire coming from the battery
. Have you tried turning the stereo on and seeing if it moves?
You not having sound could be a few things, I would tackle in this order:
-Dead channel on the Kicker amp.(Not likely, but it could happen)
Easy way to test is at the amp identify which speaker channel goes to which speaker. With with the stereo on, pick a speaker channel(one channel constitutes a +/- pair next to each other, usually labeled CH 1 or A) and remove the (-) wire. Listen for which speaker stops playing, reconnect the (-) then label the channel. My experience, people usually use channel 1+2(or A+B) are the front speakers with 1 being the driver and 2 being the passenger. After you know which channel on the Kicker amp goes to which speaker, disconnect the front driver sepaker that is not working. Then disconnect the leads from any of the three known working speakers and move them to the front driver channel that you just disconnected. If that channel on the amp is good, you should hear sound coming out of the "good speaker" you just disconnected.
-If the car still has the factory amps installed and the audio is passing through them, chances are that the amp simply just went dead. To remedy this what you will have to do is remove the door panel and take the speaker out and look to see if the amp is still connected(Pics below). If it is you will just have to run a short wire from the where the amp plugs into the door, directly to the speaker. Like Ace2cool said, most likely this is going to be the issue! Post pics if you can as you go along!
Bose amps
