Did you round out the head so that the tool no longer turns it or did the threads on the body get stripped so that it turns but doesn’t move up or down?
How to fix it goes from simple to complicated depending on the problem and what tools and experience you already have available. At worst, you may need a power drill and a screw extractor, so when you do stuff like this always make sure that you’re using the correct sized wrench. The correct size doesn’t just fit into the head, it should fit into the hole perfectly snug so that there’s no wiggle when you attempt to turn it.
If the hole in the head is just a little rounded out and it’s not bad, there are a number of tricks you might be able to try. First as stated previously, make sure you’re absolutely using the correct size for the hole. If it is a little loose in the other screw heads then order the correct sized wrench and wait for it to be delivered (or go to the hardware store and buy it in person). They’re inexpensive and it’s possible that the correct size will still be able to grab what’s left of the star shape.
You could also take something like a little bit of teflon tape, like that white plumbers tape used for sealing threads, and because it’s so thin, sometimes you can put that stuff over a slightly rounded screw head and push the tool into it and (again, depending on how bad it is) you might be able to use the thin tape to make up the gap and allow it to turn.
If the thread is stipped and you’ve never used a screw extractor before, you may want to get help from someone with a bit more experience. It’s not particularly complicated work but the risk of damaging the area around it increases if you don’t know how to avoid it and I don’t want to recommend something to you that might make it worse.
It’s something that should be simple for a person with a little experience, but I don’t recommend doing semi-destructive acts like this if you can at all avoid it, either way you will need to get a replacement screw, so you can either contact elektron support and see if they’ll send you one, or you can take one with you to the hardware store and they’ll help you find something similar.
I wouldn’t do anything else until you have a screw to replace it with, so I would make that a priority and at the same time, while you’re there you need to find the correct size tool that fits the heads exactly and is snug to avoid this problem happening again. If your tool is already snug in the hole and it stripped the head despite that then one would imagine maybe your stand is somehow putting the threads under tension and causing both a shifting of the faceplate so your button was sticking and also a tension on the screw threads which is causing them to grip the screw hole harder or tighter than they’re supposed to, so if that’s the case you probably want to consider removing your stand temporarily before you attempt further repair.
If something doesn’t seem correct when you’re trying to take something apart, don’t ever force it, try and look at it analytically as to why you’re having to force it and then if possible adjust other things that might make what you’re doing easier (like in this case, make sure the stand isn’t causing the tension).
If you somehow managed to strip the hole itself, you may need a small tap and die to re-thread the hole.
That’s probably about the best advice I can give you, so like I said it depends on what you actually mean by stripped.