There are multiple ways to gather information about FarmBot while it is running:
Almost all development for FarmBot OS is done using one of these. You can purchase one here. This will allow you to connect a PC to FarmBot to see very verbose logs about what is happening internally to FarmBot.
As of the 6.4.10 beta release a debug SSH console was added. In the “Advanced Network Settings” menu during Configurator you will be able to add an SSH public key that you can connect with. See this document for usage.
This is the least useful, but can help in a crunch. The same logs are displayed on the HDMI port, although you won’t be able to scroll them, and you are stuck either copying them or taking a picture (preferred).