Answer to "nothing happens when "on" switch depressed."Sounds like a dead mainboard again, they are quite cheap to buy though. Infact the whole machine could be replaced for the price of a board. I normally buy one with a broken screen and just replace that and the hard drive, ram etc.
Answer to "No Power to Computer"Dead mainboard Update: If you have this problem always check the charger with a multimeter, kids tend to leave laptops on bedding quilts switched on and it overheats blowing the circuits on the mainboard. I come across this quite often.