Radio powers on, looks to function, but no sound?!

I have a 2002 Dodge Grand Caravan
ES with an Infinity system. The OEM stereo powers on, looks to function
fully, but not a single speaker produces sound. It would only make sense in
my head that there is a factory amplifier hidden somewhere or these units
(White no black) attached to the speakers are individual amplifiers or are
they crossovers? The speaker I pulled out, I tested the speaker itself,
checks good. Under the hood, relay and fuse are both good. I went to
autozone and they called a hotline or something that says my model year
does not have a factory amplifier. It is obvious that the wires behind the
radio have been altered, but appear to have been returned to their
previous state. There has to be a single unit or something somewhere for
none of the speakers to work at all at the same time...the person on the
phone says there is no amplifier, but it makes more sense to me that there
would be and that it was just left unplugged from whomever had a system
in it once before? Is there? Where is it at if there is? I'm at a total loss
here!!! SOMEBODY please help me lol :-)