I have downloaded Pure OS on a usb stick and successfully booted it, after I installed it and restarted my computer. BusyBox showed up after I decrypted a disk.
Please help, I am using MacBook
First you do not need to cover the camera with Purism Electronics. 
Probably your machine is not compatible with gnu free software system. Try install linux open source system like Ubuntu in ur macbook.
I think it’s compatible because it was running perfectly from a usb. Only encountered a problem when installed
(This is not uncommon.)
I suggest you search for other topics relating to attempts to boot Linux / PureOS on Apple laptops.
Try edit the gnu_bootloader: example: GRUB CMDLINE LINUX DEFAULT=”quiet splash acpi=off” just add "acpi=off"at end to complete the line. then boot again.