I just bought a car with an Alpine stereo. It is an xboxer.It has the equalizer below the stereo. I can see that it is on. But there is no sound coming from it. It also has a little remote that was on the keyring. I replaced the battery in it. I know for a fact that this system worked. I cannot ask previous owner because he is deceased. please advise

Check the the wiring into the converter, maybe even hook a speaker up to each speaker pair at the converter to verify the deck at that point is sending signal, if that is good i would check the gains on the converter itself.
Often times they have their own gain control, make sure it is not turned All the way down (counter clockwise), if that is ok then take the multimeter and verify you are getting voltage out of the converter if you are the converter is ok, you should achieve between 2-4 volts.
If you are getting the proper readings there, then plug into the amp, and then set all the gains using a meter measure the output side of the amplifier to insure your getting the rated power (sparky has a good tool to walk you thru this and find the voltage).
If you get the proper voltages at the output stage then the issue is with the sub... wiring or otherwise... take a c battery and touch the speaker wire to the post and negative of the wire, it should make the sub move and make a slight noise... that will verify all wiring and the sub is ok.

Hope that helps.......