need help installing OpenWrt for the first time on an asus RT-ACRH17 REV 1.60 router that still has the factory firmware installed. This hardware is listed as supported and the same hardware as the RT-AC42U model router. I tried to install using the stock firmware upgrade method from the webGUI but the openwrt file was rejected as a bad firmware file (I suspect it's signature may not have matched or somesuch. ) I moved on from there and have now most likely voided the asus factory warranty by removing the 4 screws from the bottom, destroying the tamper tag on one screwhead, carefully removing the top cover, and connecting to those so nicely labeled pins on the circuit board labeled GND, RXD, & TXD with a FTDI 3v3 USB to TTL serial cable.

I now have serial console access! How can I install a working OpenWrt Firmware on this device... possibly even booting from a usb thumb drive or maybe TFTP into ram first then flash.

The serial bootlog follows and appears to give some options.... but please, the implimentation is in the details and i need help with those details as to what to do from here:

full bootlog here: https://pastebin.com/ty7m9Sss

the boot commandline interface (option 4) has a few interesting options like boot from USB that could be useful, but how would i sertup the usb stick for this option.

the other options for TFTP look useful but how do i use this and TFTP to load firmware. do I need to setup a TFTP server or client to host the firmware how is the TFTP process done

finally there appears to be a serial option. how would I install over serial.

when successful here, I'd like to setup a support page for these units to help others.