1st thing you should have done was swap the red/yellow wires at the bullet connectors.
Lots of posts about it in Electrical section.

If it's totally dead (as wired), you may have blown the ignition switch (not unknown to happen).

 

I’ve swapped the bullet wires as described still nothing. Have I likely damaged the head unit irreparably? Any advice is greatly appreciated cheers

 

Ok thanks for that. I’ll try and swap the red and yellow wires and see how I get on. when you say blown the ignition switch? The ignition still works so hopefully that’s not happened

 

Check the fuse on the back of the stereo just in case.
Aside from that you should use a multimeter on the power wires to see if it's getting 12v. Test Red to black and yellow to black with ignition on.

 

Check the fuse on the back of the stereo just in case.
Aside from that you should use a multimeter on the power wires to see if it's getting 12v. Test Red to black and yellow to black with ignition on

Check the fuse on the back of the stereo just in case.
Aside from that you should use a multimeter on the power wires to see if it's getting 12v. Test Red to black and yellow to black with ignition on.

Hi. Yes I’ve checked that all good. I’ve managed to get it working. Was weird I had to take small piece of wire to connect from yellow to red as was done on the kenwood stereo I’ve taken out. So great. Got it working. Problem now is can’t turn it off. Ignition off but head unit still on. Had this with the kenwood stereo but I could manually turn that off I can’t do that with this Sony head unit so I’m a little stumped there. I can only think there’s some wiring done a little wrong in the loom behind the dashboard