I prepared my Live USB-Stick with different software. I created a bootable device with rufus on windows, dd on linux and unetbootin on linux. I also used different USB sticks, but the following problem remains the same. I used the latest officially available iso image of elementary OS and downloaded it a few times, so a damaged image might not be the problem.
If I boot the USB stick, the first image appears. I can choose boot elementary and press Enter. After that there doesn't appear anything readable. Just lines of pixels. (I took a picture of that)
The OS does not seem to boot. Furthermore nothing happens if I press any keys or so. The image is not totaly static. Firstly just one line appears and then a few more appear. Like in the bootsequence you are used to. But it's not readable and the boot operation seems to freeze. If I pull the stick out nothing changes. I have to hard reset my machine with the power button.
It's definitly not a problem of my hardware, because I already have windows and linux installed and it works perfectly. My specs are the following:
OS: Pop!_OS 20.10 x86_64
//////7676767676*////////////// Host: private
/////76767//7676767////////////// Kernel: 5.11.0-7612-generic
/////767676///*76767/////////////// Uptime: 12 mins
///////767676///76767.///7676*/////// Packages: 3428 (dpkg), 47 (flatpak),
/////////767676//76767///767676//////// Shell: zsh 5.8
//////////76767676767////76767///////// Resolution: 1920x1080, 2560x1440
///////////76767676//////7676////////// DE: GNOME 3.38.3
////////////,7676,///////767/////////// WM: Mutter
/////////////*7676///////76//////////// WM Theme: Pop
///////////////7676//////////////////// Theme: Adwaita-dark [GTK2/3]
///////////////7676///767//////////// Icons: Pop [GTK2/3]
//////////////////////'//////////// Terminal: tilix
//////.7676767676767676767,////// CPU: AMD Ryzen 5 2600X (12) @ 3.600GH
/////767676767676767676767///// GPU: NVIDIA GeForce RTX 2060 SUPER
/////////////////////////// Memory: 2297MiB / 16016MiB