I just installed ubuntu 20.04 lts. There was no problem during the installation process. But after the reboot and choosing Ubuntu at the grub menu (I also use windows 10), it's just nothing, only black screen. I have tried to edit the command and added "nomodeset" like the others told. But nothing's changed.
My laptop is Lenovo g405s, AMD A8 processor, Amd Radeon graphic card, and using legacy mode