someone told me i can use my hp 4320s notebook direct on ac power without battery and when i did so it worked ok till shut down. The next time i tried powering it same way it wont start up but the adapter seems to be working right since the LED beside its socket on laptop is on. when i return battery in place without adapter connected and press power button, the button blinks once and no sound nothing at all is heard from the laptop and goes back to silence as thoug dead. please assist if you can........