The problem you are facing is likely do to the tea damage. I suspect you didn't remove the logic board and clean the other side as well as wash the board down with a good grade isopropyl alcohol (85% or better).
Between the acids in the tea and the sugar or milk (spending on how she likes her tea) you have a corrosive environment still present and the possibility of a short in the logic.
I would start by cleaning things again and if you are not comfortable going into your system this deep see if you can find an Apple authorized service center willing to work on a liquid damaged system.