boot – CrOS does not boot from a USB installation media

I'm trying to start Ubuntu from my Chromebook. This is a Lenovo Yoga C630. I have developer and debug mode enabled, with crossystem dev_boot_usb = 1 dev_boot_legacy = 1. I've also been running this since Ctrl + Alt + F2 Terminal: enable_dev_usb_boot. I have created my installation support with the chrome recovery utility. I launched it from the option "Use local media" and renamed my Ubuntu.iso to Ubuntu.bin. He managed to create the installation support. I then restarted my computer and when I got to The operating system check is disabled screen, I leaned Ctrl + U. I know that it is Ctrl + U because Ctrl + L is starting biosand I do not have any bios. But when I leaned Ctrl + U, my computer just beeps. I've read somewhere that it will beep when it thinks that the media is not valid. There is little documentation anywhere. I found a piece of useful things here. If you have any questions, feel free to comment below. Any help is very appreciated!