thank all
tried another power supply, the result still the same, the battary must exist even plugged AC power.

> not heard of this what happens if you remove the battery and just try powering on with the AC (no battery in) ? still the same, just use AC power can't boot up the notebook (no bios screen, only had power led on) also, the notebook sometime will display BSOD at win7 (most of time is watching movie...

After used the notebook about two years, currently the machine can't start up when plugged AC power. When plugged AC power and press the start button, the power blue led on, but other led (cap. letter etc) wouldn't light on and the screen keep in dark, even doesn't show the bios screen But when use ...