20 sec then auto RTL

Major problem. Whenever I turn my copter on and fly it for about 10-15 secs it will automatically try to RTL. I have Failsafe turned off and fully charged batteries. I have also not hit any switches or anything on the TX. Once it goes into RTL mode I cannot control it, even if I switch into Acro mode. I have refreshed from scratch and same thing happens. When I take off I am in Stabilize mode. HELP I am tired of damaging/ crashing this copter. I have 2 other copters and have never had this problem.

Thank you,

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Sorry, I am using the Arducopter APM ver 3.1 with built in compass, CUAV GPS.

I am not using Geofence
I have Failsafe turned off on the controller and APM
Fresh batteries

Based on the log and what I am watching it do it seems like it is auto switching into RTL mode.

See below for the log

Thank you