I have the 2200 A.Q. amp. The grounded wire got hot enough to melt, so when being replaced the power wire was still connected. When connecting the ground back to the amp it caused a popping sound and white smoke to come from the amp. Is it ok to try and reconnect it still or would it have caused damage to the amp.

It sounds to me like it was already shorted, hence the ground wire getting hot enough to melt.  The last time you connected it and it smoked finally blew out whatever was causing the short.  

 

In other words, it's already toast.  You're gonna have to pull it out and send it in for repair.

If the ground wire melted? That a definite short... chances are the PCB is shorted from possible overheating.Or could be as simple as a Burnt/shorted capacitor,resistor..If you can pin point the issue they can be had for much of nothing a your local radio shack..If I had to guess  it is a resistor that steps down the voltage flowing through you PCB.....If you find the problem circuit...And can give me a description I can  lead you in the right direction.

When i called it in and asked about it. The guy told me that because the power wire was not disconnected, the amp may have still been holding a high amount of power because it had not been discharged causing it to back charge.

It sounds to me like it was already shorted, hence the ground wire getting hot enough to melt. The last time you connected it and it smoked finally blew out whatever was causing the short.

In other words, it's already toast. You're gonna have to pull it out and send it in for repair.

When i called it in and asked about it. The guy told me that because the power wire was not disconnected, the amp may have still been holding a high amount of power because it had not been discharged causing it to back charge.