Has my device expired because I opened a screw?

When I bought this device, I loosened a screw at the back because I wanted to see how many sockets my mainboard had, as I only had 8GB RAM and wanted to upgrade if necessary. However, I did not disassemble it, just loosened one screw, as I made up my mind a short time later. So even if you notice that the screw has been loosened, you can still check the other screws, right? So the ones that I haven't touched and with a loose screw you can't disassemble the part.

My laptop breaks down, so I just want to know whether the guarantee is still valid and I can have it checked by a specialist. Otherwise I would ask a relative who would take this apart for me.

That depends on the guarantee conditions.

Normally the guarantee is still valid

If it were a PC that wouldn't be a problem. The seals on it are only used to check the completeness.

But you should only unscrew a laptop if you know what you are doing. Someone who doesn't get the idea to google his motherboard on the Internet probably doesn't know that.

The single screw is probably not a problem, but you shouldn't do that for the future.

No. PCs are so-called open systems. The guarantee does not expire. If something was improperly exchanged, it can look different.

The way you describe it, it doesn't matter. But note the difference between guarantee and warranty.

There was once a court ruling that the warranty rights of a PC must not expire by opening the housing, since upgrading computers is a completely normal process.

However, I don't know what is in the warranty conditions for your device. Guarantee is a voluntary service, so the manufacturer can also formulate the conditions according to his taste.