I'm not sure whether its hardware or software problem, but as I have reflashed software and reset the device multiple times, I suspect hardware. Here are the symptoms:
After successful flight i tried to connect APM via telebee radio. Telebee's didnt link, so i brougt the usb cable. On mavlink conncet it reads all params up to "got AHRS_RP_P" and then the reading stops, until it gets the timeout. the detailed error message is "got 224 out of 256 params in 6 retries".
I tried flashing the software- overwrite my arduplane 2.68 with arducopter 2.91, then installed again the arduplane firmware. The error remains the same.
Most of the reports of freezing during connect have been the sensor init failing in the background .
Check for error during boot in the Terminal screen and test the sensors in cli