I tried all possible paths,
All i get is error: "cant find command line root" I have no experience with grub, and I just want to install ubuntu on an old macbook pro (overwrite whole thing) please teach me (been hours)
An alternative way to try to boot to the USB is to restart the computer and hold down the option key.
You should see a row of icons representing the bootable devices found, the USB would be an orange one with a USB logo on it, if it shows. Hopefully it does because then just highlight it and click the arrow underneath (or press enter).
