Linux not reading /boot directory off of USB

I'm attempting to run 32 bit linux off of a usb for an old XP machine. There are important files on the computer's base drive, so formatting or partitioning isn't on the cards. So far I've tried AntiX and Debian, and in both cases I was sent straight to grub repair with the error "/boot/grub/i386-pc/normal.mod cannot be found". Using grub rescue I identified the correct partition, and can use ls to see the list of folders to find the /boot folder, however any attempt to ls into the boot folder produces an empty line before returning the command prompt. Examining the usb with a different computer, the normal.mod file is there in its correct place, however the boot folder and a few other folders cannot be written to or modified due to permission issues which I can't figure out. My best guess is that grub simply isn't allowing itself to read the boot folder, but I'm not sure