Safe as no erasure of your data is done. See it in the CNET Laptop Troubleshooting forum at link.
Be sure to unplug all USB things when you do this.
my dv4 1120us laptop is not coming on.i plugged in the original charger and there is no lights ,noise etc. i plugged in a different adapter and the led light in front ,next to the power light just keeps blinking.when i press the power on button it starts booting for at least 3 seconds an cuts back off....please help!