I would like to install openwrt for the first time on my Ubiquiti LiteBeam 5AC LBE-5AC-Gen2 devices without having to open them.
the WIKI is not of much help.
The WIKI just says "connect it and do it", but not how to do it.
OK, start TFTP server.
Then "Connect serial console"
OK but where connect the serial console? How?
That's the "open them" part.
I do agree with the OP that it would be helpful to include pictures showing where the serial connection is located and how to open the device. I think that would make the guide much easier to follow, especially for people who are doing it for the first time.
Sure, but OP wants serial free install.
Photos of the PCB are available via FCC - https://fccid.io/SWX-LBE5ACG2.
I can't really comment much on that. If the only supported way to flash the device is through the serial connection, then that's probably why it's the only method documented. If there were another supported way to flash it, I'm sure it would have been considered and included in the guide.
These can be flashed to OpenWrt without opening the case. The "Ubiquiti common directions" or something similar has a way to do it. I can't find that in the wiki right now though.
The overall procedure is:
Downgrade to a specific stock firmware.
Log into stock firmware CLI.
Patch fwupdate.real so it ignores the firmware signature check and can flash unsigned firmware.
Upgrade with "factory" OpenWrt.