i have dell 1558 laptop.
each time i press start button it does not start than again i oress start button than the laptop get start normally. during first press nothing happens, even the start light does not glow.
Are you comfortable with opening the case and doing some diagnostics? If you are, I can tell you the details of unplugging the 'ON' connector on the motherboard and shorting it, and checking. Let me know.