Sometimes its as easy as swapping over the red and yellow connectors (switched and live feeds) but as yours doesn't power up at all I suspect you may need to run a new live feed from the bus bar behind the fuses. I think it depends on what year the car was made

I have a 51 plate and had a similar problem but was only changing the head unit because it had bluetooth for my phone, put everything back to original and swapped the head unit for a TomTom with phone feature instead, much easier for me.

Stu.

 

got it sorted now thanks. just chopped every wire on adapter and used a multimeter abd a power probe to rejoin them all but the speaker wire were wrong

 

Mine is a 2001 on a Y reg. When i first plugged mine in it didnt work, I unplugged it all and plugged it all back in again and it all worked fine. I think someone had been at mine before however as there was a lot of cut and rejoined wires etc... in the original loom so probably a slightly dodgy connection somewhere...