Studio XPS 435T/9000 would not turn on

My client called to say that he could not turn his computer on.

I determined that the power switch (the ON button on the top cover) was faulty. 

To fix this you need to replace the entire top cover, Dell part number H310J, a part which is still available on the web.  You will need the remove the front to remove the top cover.  Disconnecting and reconnecting the power switch is the hardest part.  Don't forget to remove the part from the old one that is the connections to the audio and USB ports and install it on the new one before you struggle with reconnecting the power switch.  A power switch is just a hardware part, but they only last so long.  If your Studio XPS will not turn on, this could be the problem, and it is fixable.