Can't boot Linux Mint

I recently installed Linux Mint on an old HP Chromebook x360 and I can’t figure out how to boot it. I installed the RW_LEGACY firmware and when im in the boot menu I don’t see the option for Linux Mint.

dual booting with ChromeOS or not? RW_LEGACY firmware is for dual booting. It also doesn’t support UEFI NVRAM, so custom boot entries are not available

this is covered in the docs/FAQ

I’m trying to dual boot with ChromeOS.

the FAQ addresses this

I can’t find it in the FAQ?