A question with wiring from fuses

Hey I am tryin to install a head unit in my car, ive installed a few before and i know how to do it, but whoever had the car before me had a full system its obvious, and he did some things with the wiring. I couldnt find one of the power wires (12 volt ignition) and its supposed to be blue, there was a blue wire but it is connected to a fuse. Will this wire be the one I am looking for? I have connected it and connected the 12 volt battery wire, and ground and i am still getting no power. Any suggestions?

Try using a test light to find the fire you need. Turn your ignition on and probe till you wind the hot wire. Then turn the igition off while you are still touching the wire with the test light. If the test light goes off you have found the wire you are looking for

its not blue, blue is for your remote att or remote amp.

red is for constant (12 volts) and yellow is ignitions