The pickup and preamp we use in all MacKenzie & Marr guitars requires a 9 volt battery. The most common reason for not getting audio output is that the battery is either not installed or still covered with the protective clear plastic casing. Because we refuse to cut a chunk out of the guitar's sidewall we've elected to use the Fishman Sonotone system which has a battery bag inside the guitar - usually attached to the neck block just forward of the sound hole. Check to make sure there is a battery in the bag, the battery still has a charge and the red and black twisted pair wire is securely attached to the terminals.
If the battery is fine the problem may be as simple as raising the volume. Both tone (bass to treble) and volume are controlled by small wheels on the control module located inside the top half of the sound hole.