Push in the button before you turn it on. Turn the knob while still pushing in the knob and don't let go until all the lights light up. Press it once and you will see the software version like 3.826, etc.
I've heard the V1's mute button won't work if you try to use a cord from another detector.
Did you buy it brand new or used from somebody else? If you bought it used, it could be a cord that just powers it up, but it won't allow you to mute it or change modes. I have heard that a V1's cord is a telephone cord with 4 colored wires inside of it as opposed to only 2 colored wires inside of Bel or Escort cords.
Does it push in at all? If not the button might be broken. I remember seeing a thread a while back that someone turned the knob past the stop point and broke it completely. He had to send it to v1 to get the knob completely replaced
Yeah it does push but nothing seems to happen when I push it :/
What about trying with the cigarette plug just to see if it is the hardwiring that is the issue.