My senior project group bought a new APM board set about a month ago and had been testing out waypoint flight/landing in the Xplane simulator and stabilize mode in real flights with a lot of success. Then all of the sudden, the LED's on the IMU board start acting differently when powered up and we realize there is no longer any gyro data output from the APM. On the "Flight Data" screen in the mission planner, no roll or pitch information is showed on the HUD. And when in stabilize mode, the plane does not respond to being rolled or anything. Everything was working last Monday, we took a couple days off to work on other things and then Thursday it was doing this....

For all of January, the LED's on the IMU board acted as such (switch in Flight mode, away from the RC pins):

• Power on: A and C would flash back and forth while the gyros caibrated
• Then B would go solid and C would blink waiting for GPS lock. A off
• The A off, B solid, and C solid, Gyros calibrated and roll/pitch showing on the "flight data" screen, GPS lock.

Since Thursday, Feb 2nd,the same LED's act as such:

• Power on: A solid. C blinks slowly. B never comes on.
• A remains solid no matter what is done. C goes solid after GPS lock.

We are also confused cause the "Correct LED Behavior" page (http://code.google.com/p/ardupilot-mega/wiki/LED) seems to have changed since the winter. We could swear that it used to say that B solid and no A LED was a GOOD thing. In fact, it said that having A solid was never good unless you were in CLI mode. But now it says differently and that solid A is correct. Why did this change? This also doesn't make sense cause there is another senior project group using APM that is getting the first described LED behavior (where solid B is good and A is bad) and their boards are working perfectly...

We have checked for shorts in the boards, bad solders, or any physical damage and there was no flight crash that could have caused this. Interestingly enough, in CLI mode, the "adc" test does return gyro readings that change as the board is rolled and tilted, so we know the hardware is working...we think. We suspected a firmware issue but after wiping the logs and the parameters and factory resting the board and uploading new firmware (from Mission Planner version 1.1.31), there was no change in the issue.

Please help!! We are running out of project budget and cannot afford to replace these boards again. Also running out of time before we need to test the project for our professor. Thank you!!