Documentation touch-ups are in on our backlog.
However, if you would not like to wait on us and want to make your own edits or updates in the meantime, the documentation is all open source and available on GitHub: https://github.com/OnionIoT/Onion-Docs
If you make a Pull Request with your changes, we'll review it, accept it when it's ready, and the changes will show up on docs.onion.io !
power OFF your Omega2+
press and hold down the Reset button (the momentary push button between the FW_RST pin and the +3.3V)
switch the Omega's power ON
and after this you should see the UBoot menu on the serial console...