Hello, trying to install OpenWRT on a Meraki MR42. I get to step 4 on https://openwrt.org/toh/meraki/mr42 but unable to load .itb image using bootm:
Has anyone come across this before with u-boot, and if so, how did you fix it?
Managed to get it booted into the initramfs but there’s no mbn file in /root. I’m having difficulty working out how to transfer this file over serial as there are barely any tools available on the initramfs.
Hello,
Did you manage to do it?
Yes, just follow the instructions for it, don't go and download any other files 
Files: https://openwrt.org/toh/meraki/mr42#:~:text=u-boot%20and%20initramfs%20images