LEDs Meaning on rev.3.x S300 Boards

DIAG LED can be found near the USB connector.

DIAG	Meaning
Rare Flashes	ECU NOT Powered. USB Connected.
On	ECU Powered.
Data Transfer	Datalogging or Programming ECU.
Blinking Fast	RAM or MCU Fault.
Blinking Slowly	NVM or BT Fault. Boot Mode Active on Device.