Hardware Repairing 3ds

[splinters]

Have a friend who has a 3ds that is intermittently faulty. Everything powers up fine but the buttons and touchscreen stop working...but not all of the time.
Will see if there is a pattern but I am happy to open up and reseat connectors, replace touch screen etc.
Is there any know problem and quick fix, does a particular board or connector control the buttons and touchpad?
Just want to fix it up enough to trade in for a 3ds XL so cheapest fix possible.
Any ideas?

 

[The Milkman]

NO.

Tell him to send it back to Nintendo. If you open it and make it worse (which im guessing you will since your asking a question like this) then your friend is royally fucked.