02 ram quad infinity amp?

I have a customer's 2002 Ram quad cab truck in my shop.  I installed 4 new speakers to replace the ones that were blown, kept the OEM head unit and infinity amp that's behind the glovebox.  The driver door speaker won't play, so I'm assuming the amp is shot. 

Does anyone know the part number, or where I can find a replacement amp?

Is there any alternative --> install aftermarket cd player, bypass amp <--doing that, would the fronts still sound as good?

No, they did not.

Im leaning more toward the amp being shot then anything.  Anyone else?

For one, I don't believe in a bad connection on factory wiring.  The truck hasn't been modified, so I find it hard to believe that any wiring has been damaged.  Connections on the amp and radio look fine. 

It could be the radio, but I'm thinking the amp would be bad before that.

The customer picked his truck up yesterday and reported back that the right side front and rear speakers are staticy now.  Drivers left rear doesn't work, drivers front works fine, and sounds fine.