I have a TRB140 that I unwrapped from the box and connected to power, and all it does is light up all the LEDs but one (it happens the moment it gets power). Is there a document describing the various possible scenarios for these kind of error codes?
As you can see, the second signal strengt indicator light is off, rest is on.
Please follow this link to learn about TRB140 LED's: https://wiki.teltonika-networks.com/view/TRB140_LEDs
It may be that your second signal LED is simply not working. Can you confirm that everything else is working (mobile connection, etc.)