Without a schematic a multimeter will tell you very little, you may be able to measure 9 volts,etc. here or there but you won't know if you should have voltage there. Check your solder joints, 9 times in 10 when I have a problem like this, it's a bad solder joint or worse, I've soldered something to the wrong spot. Look carefully at the existing wiring in the guitar, did you knock a wire loose there, I know that sounds obvious but it happens. The down-side is even if you can check it, if it is fried, there's probably nothing you can do about it, most preamps ( onboard ) can't really be fixed at the circut board level. Check the connections, I'll bet that's it, also check the solder traces on the circut board, sometimes they "peel up" if they get too much heat. You can use the meter to check continuity and power, but if it was working when you removed it and you didn't crack the circut board taking it out, I'm still thinking connection.
Good Luck,
Scott ( BassVI )