I've got APM 2.5 last week and decide to build a octocopter :-)
I did all ESC tests and calibrated them. I use parallel BEC when connecting to APM2.5. I have tested without props and everything is fine when I connect USB cable. When USB cable is not connected, APM board does not show any signs of being alive.
I have tried to use power distribution board from my other quadcopter. Even if I connect only 4 outputs thru power distribution board, the result is the same... nothing. When I connect the same power distribution board to my old APM 2.0, it has blinking lights.
Am I missing something with new APM 2.5? or I just have to return board to 3DR..?
Assuming it was an unassembled kit, did you solder the JP1 connector and place the jumper on it?
@Chris: Thank you for prompt reply.
it was an assembled kit. JP1 was not there as it was delivered I guess. I placed a jumper on JP1 and it connected without USB perfectly.