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 v15 release, SSH access has been completely removed from FBOS.
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).