Inside the housing of an OCZ Agility 4 SSD I found several additional connectors on the opposite site of the SATA connectors.
What are they good for and how to connect them properly?
J5 looks like a UART connector and the
JT_ pins are likely JTAG. UART should give you console access to manufacturing/diagnostic commands, and JTAG should allow you to the debug the code (firmware) running on the controller CPU.
As for J3, at a guess, ROM/FW allows you to switch from the firmware stored in the flash to the built-in CPU boot ROM (e.g. in case flash is corrupted and firmware can't boot properly).