my laptop dell inspiron 6400 take several times press up of power button to boot. when i press the power button it turns on but there is nothing on the screen, whereas when i press it again and again as turning off by pussing for a while and again push it to turn on it starts in multiple times.
OK, so you have two listed problems here, but I not sure your question is coming across correctly.
You say it won't boot (meaning it won't start up), however then you say it is booting, just not showing anything on the screen. So, which is it? Not booting at all, or not showing on the display while it is actually turning on and starting up?