I have a Compaq Evo N620c laptop that we bought from someone who refurbishes computers, so it was used. I knew it needed a new charger so I got that, and it worked fine. Then I took it out of town, plugged it in as soon as I got there and was able to use it. It then sat unplugged for a few days. After flying home, I can't get it to power up whatsoever when plugged in. I unlock the battery part and kind of mess with the battery, repositioning it, and it makes a whirring noise like it will start and then ultimately doesn't. Does that sound like the battery? I thought you didn't need the battery to use a laptop?