I'm new to Ubuntu (and Linux in general), and I'm trying to install 21.04 on a 2010 Macbook Air from a USB. When I restarted it after I went through the installation process (wiping the disk in the process), I was left with a white screen. It also leaves me with a white screen after I power it off and back on again. I can't go into recovery mode or safe mode, and the only thing I can do is hold option/alt after it starts to go into the startup manager. I can use that to boot into the USB, however, which I might be able to use to fix things, if possible.
I ran boot-repair from a live USB which gave me this information, which I hope can be of use: https://paste.ubuntu.com/p/yBCfwYxDJT/