Check the wiring under the dash, loom everything down there, maybe the fuse box. Check it! Hard to tell with the description you have given. As you may have cut the wrong wire too.

If you remember cutting, pulling or using unnecessary force on a thick yellow wire. You may regret trying to do your head unit install lol.

Only reason i say this, cos I know you have to remove alot shiz to install/uninstall HU into an ek.

Simply pulling it out with force and cutting whatever is attached is not the way to tackle this properly.