If it shorted the pcb then most likely blown the mosfet. Not definate but likely.
To set the amps up i use a 60hz tune then set the gains with a multi meter. If u go on google n type in setting amp gains using a mulimeter. If set correctly then it will stop the amp clipping causing either damage to amp or speakers.
Most common
problem with wiring of subs is when u alter the ohms.
Will try find the link that has a very good detailed write up.
http://www.edesignaudio.com/edv2/gains_video.php
Pros: Easy and fast
Cons: Some people don't like math, it's not amazingly accurate, and as cheap and useful as they are, some people don't own a multimeter
Required Equipment: Digital multimeter capable of reading true rms AC voltages
Probably the two most basic equations in electrical analysis are Ohm's law (V=IR, V is voltage, I is current, R is resistance) and the power equation (P=IV, P is power). When you combine the two, you get P=V^2/R. Rearranging this gives us P*R=V^2, or V=sqrt(P*R). This means that if your amp does 100rms at 4ohm, we have that V=20. In order for this amp to actually do 100rms @ 4ohm, it would have to put out 20Vrms on the speaker terminals. Unlike methods 1 and 2 above, this method depends on the power rating by the manufacturer to be exactly right in order for your gain to be right. If the amp is overrated, then by following this method you might actually be clipping the amp at full volume, and if the amp is underrated, then by following this method you might not be able to reach the full potential of the amp. Another disadvantage is you have to rely on the accuracy of your dmm, and many can be pretty innacurate, especially with AC signals. However, it's easy and fast, and some people like that.
1 - Use the equation above to determine the proper output voltage for your amp's power capabilities. If the amp does 1000x1 @ 1ohm then you want 31.6V, if your amp does 50x4 @ 4ohm then you want 14.1V per channel, etc.
2 - Turn off all of your headunit's processing (crossovers, EQ, etc) and if you have an Alpine, set the bass level to the full +15.
3 - Turn your amp's gain and your headunit's volume all the way down (counterclockwise).
4 - Unhook all speaker(s) from the amp, set the multimeter to AC voltage and hook up the leads to the + and - on one of the amp's channels.
5 - Put on a test tone near 50hz for all amps. Use this frequency because dmms are generally most accurate around 50-60Hz, and as long as your speakers are all disconnected they won't be damaged.
6 - Set your headunit's volume somewhere around 3/4 of max to ensure it isn't clipping and remember this volume setting.
7 - Now it's time to start turning up the amp's gain. Simply turn up the amp's gain until the output voltage matches what you derived earlier.
8 - If you're at this step then your gain is set, all you have to do is remember the headunit's volume at which you did the test and you're set. Remember also that you should not turn your volume higher than this setting unless what you're playing is recorded at a very low level, or else you risk clipping. Another thing to remember is that any EQing that you do will change the point of clipping, if you have anything boosted more than a dB or two then you should try to stay a good bit below this maximum volume found in step 6 or you risk clipping at those boosted frequencies.
You need to download a test cd 50hz-60hz