Firstly sorry for the long post
I've got a 2.2DTI. Everything was fine until a couple of weeks ago.
Passenger side door locked and couldn't get it to open (central locking or manually), at the same time, my lights were going on themselves, reverse lights on, indicators not working, handbrake light on (even when the handbrake was off).....basically possessed

Brought it to a mate of a mate who's an indy mechanic.
He had a look and had to remove the glovebox to get to the fuse box behind the passenger door, turned out the previous owner had put a wire across a connection instead of a fuse. So had to get the fuseboard replaced.
Then the "mate" said the ECU was fried and I needed a new one so all in would be €400 to fix. He fixed it and everything was fine....for 2 weeks, now the same thing has happened again. Now I never saw any of this and was just taking his word for it.

This time I brought the car to my bro who's an engineer and like his cars.
He said the ECU was never replaced!! The bolts holding it onto the bracket are rusted and obviously never removed, plus the ECU is filthy, similar to all the components around it. My brother thinks the "mate" may have just reloaded the ECU as the connector looks like it was removed/cleaned.

So does anyone have any idea what the problem could be? Could it be a relay causing the problem? Or is it actually the ECU?
PS if this post is in the wrong place please feel free to move it