Let me guess: You tried running info-beamer pi on the Pi4? If so, that doesn’t work at the moment. The Pi4 is the first time the Pi is incompatible to its predecessor. OpenGL works completely different and the current info-beamer pi release “gets stuck” currently trying to use OpenGL. It might take a bit until info-beamer is as polished on the Pi4 as it’s on earlier versions. See also Raspberry Pi 4 release and info-beamer information