"I installed a battery and now I get s gps lock almost immediately on power up (8 to 13 sats in view in a minute). I also have no JP1 installed and only power the apm2 from the input rail using a ubec that outputs 5.03 volts. Anything much higher…"
"Check and make sure that you can read the prop size on each prop from above. When I built my y6 I put the bottom props upside down at first and could not take off. Just make sure the top of the prop is facing up. "
"If you press and hold the left menu button (+) it should bring up the radio setup menu. Scroll down to the bottom to Mode.
I had the same problem as you and I picked Mode 2 RUD THR ELE AIL to fix it. This works for me with er9x."