I decided on cleaning my laptop fans today, which I've been procrastinating for about a year now because of this one screw. But I just can't seem to open this with my screwdriver, since whatever I did back when I last opened it it's nearly circular now. Is there a way to unscrew this?
If you have a Dremel, grind a slot into it and unscrew it.
If it has a hard backing, you can place a flat head screwdriver on it, give it a few taps, apply loads of pressure and turn it out.
If none of these are possible, a drop of CA adhesive on the screwdriver head, push it against the screw, make sure there is no excess leakage, then use a quick set spray. Once the screw has been turned out, use acetone to remove the glue.
If all of this fails, you gotta drill it. A hand crank drill, and a left handed bit. People seldom have these, so I assume this is your last resort.
Final bit of advice, hit the screw head a couple of times before you try any of these as it loosens the screw a tad. Also, sharpen an old screwdriver tip to just the width and thickness of what is left of the screw head slots. You should be able to find one that is already this size in those screwdriver tip sets
If you have a Dremel, grind a slot into it and unscrew it.
This has saved my ass many times. I keep one of those diamond coated wheels on a spare cutoff mandrel already mounted up pretty much specifically for this purpose.
Harbor Freight has a pretty cheap left handed drill bit set that is sometimes a lifesaver in these situations. Many times I just start drilling it with the left hand bit and often the bit grabs and unscrews the screw before even getting to the phase of trying the screw extractor on it. Sometimes not.
Do you have a large Philips bit (like #3 or #4, the largest one that will fit in whats left of the screw)? You could try using that and tapping the end with a hammer (not too hard since its plastic) while gently twisting it. This usually shocks the screw and breaks it loose.