Car Stereos: No Sound, mercury sable, amp settings

Question
Ok, so I have a 96 Mercury Sable LS and Im having trouble with my audio system after having my friend, who said he knew what he was doing, hook up an aftermarket amp to my alpine type-s speakers.. So I bought a wiring harness kit from Scosche to bypass the factory amp to my HU. then my friend says I don't need to go through all the work wiring the speakers from the amp to the doors. he said that I could splice the speaker wire from the amp into my factory wiring and it would work just the same.  So i let him have control over the project and sound came out of my speakers really low, then when i tried to adjust the amp settings, they turned off and i havent had sound in my car ever since. i get power to my HU, just no sound at all.  I figure blowing all 4 speakers at exactly the sam ime is highly unlikely, and if my HU (PIONEER P5000UB) has an internal amp turn-off, I have no idea how to turn it back on...
PLEASE HELP!
thanks,
Chris

Answer
Friends don't let friends work on their radios (unless they are willing to make it right).  Just kidding, I run into this all the time.  I a have a couple suggestions for you.  First, the wires coming out of the new amp must be spliced into the wires going to the speakers.  They cannot be spliced into the wires that are going to the factory amplifier.  That would overpower the factory amp and cause it to stop working and no sound.  If the wires coming out of the new amp are spliced into the wires going directly to the factory speakers, then it may be the way the new amp is wired up.  Is the new amp grounded properly?  Are the power and switch wires hooked up to the right wires?  It sounds like one of these is the problem.  After all of that wiring has been connected properly, you might start to look at the settings on the radio.  I do not think that is the problem though.  Hope this helps, Scott