I am unable to arm my PX4. I get the error message EKF High IMU Accel Bias. Any suggestions ?
Please upload a logfile 
Thanks for the response. I have solved the arming problem but the motors do not consistently start at the same throttle setting. If you have any suggestions about that I would be grateful I have never uploaded a log file before and I am not sure how that is done. Best wishes.
Many thanks. My calibration problem vanished when I downloaded QControl V3.3
I am now able to access the log files and can forward them.
All good you might think but something new is wrong. The buzzer only makes a faint scratching noise there is no “main” LED and the board no longer connects to Q Control. I am not sure how it has happened but I fear the board has been “burned”, I am inclined to suspect the random fitting and removing of the power battery and the USB.
I am grateful for your help but autonomous flight has eluded me several times before and perhaps I am intellectualoly unsuited.
My last message was a touch dismal. On a brighter note a replacement has been ordered. One more try. Thanks again, Your prompt responses have raised my hopes.
The new board should be here within days. I really do not want to damage it. I think I may have done damage with repeated usb connections to and from Q Control. I have not seen a “safe disconnect” option and I am uncertain about connecting/diconnecting motor power when USB and Q Control are connected. Advice please.
Hi, for hardware related problems/questions, please give us much information as possible, e.g. which board do you have? (Pixhawk, Pixracer etc). But in general, connecting USB and power should not be a problem AFAIK
My new Pixhawk (2.4.8) board is set up. After completing the basic tests the summary shows a green light in all departments except Safety. Error messages this morning show. Pre flight fail Mag 1 Uncalibrated; No Valid Mission; Mag sensors inconsistent; Rejected Alt Control Distance exceeded 8,6m.
Of those it should be noted. The device is indoors attached to the computer. No Mission has been drafted.
The log file shows no files recorded.
when USB connected 12 satellites are found with good horizontal precision within 2 minutes (average)
When battery connected (without usb) there is no sound from the buzzer and no main light. Attempts to arm fail 5 minutes after power up.
On battery power there are five minor LEDs illuminated: two green, two orange and one blue (flashing)
The arm safety switch flashes fast and does not respond to switching.
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I have made some progress.
I can now arm it and spin the motors but only while the USB is connected.
My ESC’s have no red wires! Is that the problem? How should I fixit?