The head unit pulls out with out unscrewing anything. You need two wire hooks to pull the head unit from the housing towards the steering wheel.It's a press fit in the dash panel.It is advisable to remove the steering wheel to facilitate removal. With SRS in the steering wheel you must disconnect the battery for at least 30 minutes before removing the SRS to prevent deployment of the air bag.
You will also need to have the radio code to code the radio after reconnecting the battery.
Due to the complexity of the unit it is advisable to replace it with a used unit.