97 Nissan Pathfinder alarm

Today I went about getting ready to install my car security system. I removed the necessary panels, and marked all the wires I needed to connect to. Next I laid out my alarm system on the work table. Then I wanted to verify the wires I marked were the correct one, by checking them with my DMM. I hadn't done the first wire when I noticed nothing came on; instrument cluster did not come on, when I depressed the clutch pedal the engine did not start. And when I turned the ignition key to accessory my power windows would not go up. I am scratching my head thinking what did I do wrong? I did disconnect the battery for about 10-minutes, and figure I created some error codes in my SUV's engine module? I have a 1997 Nissan Pathfinder, and I am installing a Boomerang-a security system (aka Aladdin 2000). After I cleaned up the garage, and reassembled the interior I did check the fuses, and all appeared good. Can you folks think of anything else I should be checking?

did you check the main fuses inside the hood, did you install the alarm or not?how own your mind, control your life.

MECP certified. always use a DMM

I did not install the alarm system; I hooked up my dmm to the wires of the ignition switch, and turned the key to check the voltage. When I turned the key and nothing came on, I wondered what the heck did I do wrong? The only thing I could think of, was disconnecting the battery. All I did before this was remove the necessary panels to route wires, and install the main alarm box. I will check main fuses.