This was super depressing to read. I guess we will have to wait for somebody else to try it...The bad news is that the screwdriver managed to "screw" my screw so to speak, and after having tried to unscrew the screw with other screwdrivers without success, I simply gave up. There is simply no way that I am going to be able to unscrew it on my own. It's not budging.
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Well, sorry guys, I will have to return the SSD :/
I'm pretty sure that the internal SSD screw is a Torx head...T5, I believe. You sure you had the right driver? You definitely don't want to try using the pentalobe driver (for the bottom case screws) on that screw head.
If you have any friends with a steady hand and a serious workshop hobby (that you can trust), somebody might be able to cut a notch in the stripped head that is good enough to get the screw out. At that point, pitch the screw and replace it with a new one (maybe even one with a Philips head). The thing you are going to have to be careful about is making sure that no metal shavings get spread around inside the computer.
-- Nathan