89 accord stereo issues

Okay, I have an 89 accord with what I believe is the stock radio. It doesn't have any markings on it as they are worn off but it is hooked into the stock harness. Now I tried to install a CD player when I first got it but could never get it to work, I figured the CD player was bad or something so gave up and forgot about it. Now my friend just gave me his old jensen head unit which was working fine and I wanted to install it. I looked up the wiring for the 89 and matched the +12 battery, +12 ignition, and ground to the correct wires on the head unit (the wires are listed on the top of the unit for easy reference). The problem is when I turn the car on all that happens it the button which says "Jensen" lights up blue but nothing else. The only wiring problems I ran across were that the head unit had no wire for the dimmer so I didn't hook it up and the car had no wire for the power antenna so I didn't hook that up. Shouldn't the head unit come on with the +12 bat, +12 ignition and ground all hooked up? This is the same problem I had with the last head unit so now I'm thinking its something I'm doing wrong. Any suggestions would be great, thanks!

little update... I checked the wires with a voltmeter and the one that was supposed to be ignition had +12 with the car off, the other had 0 but went to ~3 with the car on. So I figure I somehow got those mixed up and switched them. Now I get no light behind the power button but the unit does make noise inside like it's looking for a CD or something. Should the wire that is at like 3 volts (ignition) be at 12? If so why would it only be at three? Should I have switched these wires even though it goes against the wiring diagrams I found? Anyone have any suggestions to get this thing working?