APM 2.6 ABC LEDs don't light, Can't connect to APM

So I set up and programmed my APM and sensors according to the directions. I ran a pre-flight test indoors without props and everything seemed perfect; motors spinning as expected, good GPS lock, sonar working, telemetry working, etc. I take it outside and power up and I can’t arm. I was thinking I failed the prearm safety check.

Went back inside. Tried to connect to Mission Planner over USB; connection failed . Tried to connect over telemetry; connected but it took a long time. HUD says no GPS lock. UBlox GPS unit has blinking blue LED and GPS test gives me lat. and long. so it is working fine.

I noticed that the ABC LEDs on the board aren’t doing anything. If I hit reset, the blue light blinks a few times and goes out. Red and yellow never light. RX/TX lights constantly flash. Now I can’t connect to Mission Planner at all. Not through USB or telemetry.

Checked fuse and it passes a continuity test.

Something is really wrong. Not sure how to diagnose this. Any help would be greatly appreciated.

If you can talk to your AMP through the Terminal Tab CLI, try doing an eeprom erase. That has helped some members who have described the same symptoms as you have.
TCIII Developer

It was the eeprom afterall. I erased and reset. All is well now. Thank you.