Major alarm/electrical problem

[MGWade]

My 1999 Boxster got rained on and flooded. Lucky this never happened so badly in all these years, I guess.

Thanks to info here and elsewhere on the interwebs, I pulled the ECU and cleaned it up, as well as clearing out the puddle. It started working again and even runs smoother than it has in ages! BUT, the door and trunk locks and windows do not work.

QUESTION: Do I need to open up the covered boxy bits on the ECU and clean those to resolve this? Is that even doable?

I did check the fuses, no problem there.

What steps do I take to fix this as affordably as possible? (Like, if I have no alternative to a new ECU, where do I get one to install myself now that I know how? I have read that you can only use a brand new one because the access code (or whatever it's called) is only good one time.)

Appreciate any hints.