white noise coming from subs?

I know.   Do you have an ohm meter?   All of the output devices that are directly connected to the exploded one need to be replaced.  With the meter we can determine how many of them are shorted.  Once we find that out, we can cut the shorted ones from the equation and see if the amp will play properly with the remaining transistors.  The only thing this will do is let us know if there are other problems, or just the shorted outputs.  Once we cut the shorted devices out, you need to reinstall it and see if the noise is still there.    If you have a meter and want to check it out so I can let you know what you are looking at to get it repaired. 

Are the number on the FETs  IRFP3415?

Did the metal screen mounted to the inside of the plastic in the center of the amp fall into the amp?  You are probably looking at a 250 dollar repair.  (Assuming the other 8 outputs are OK) Those transistors are soldered to those strips.  DO NOT TRY AND REMOVE THEM WITH PLIERS.  You must use a torch.