I created a bootable USB with Ubuntu 20.04 on it and I wanted to test it on a working Ubuntu 20.04 Laptop whether it works. This was apparently not a good idea, because I get dozens of SQUASHFS-errors and I cannot do anything at the moment (I pressed the on-off-button several times, but the laptop still won't turn off). I am pretty sure by now (since I already removed the flash drive and checked it on another computer) that the flash drive is corrupted.
This is not a huge problem, what does annoy me is that I cannot use my laptop. I cannot take the battery from the notebook (it isn't removable), so what can I do (it probably still has around 5 - 10 hours battery life-time, and I wouldn't mind having my laptop soon)?