"Ronald, thank you very much. Your solution worked. We identified CTS pad on the PCB of the radio module, and cut the trace to it. Now the radio module starts fine when I plug in the battery to the quadcopter.
For those "lucky" guys who end up with…"
"Ronald, hi. I'm an unfortunate owner of the exactly same 3DR telemetry module, ordered at banggood. When I connect main battery to my quadcopter, the telemetry module goes into Bootloader mode, and red LED goes solid.
May I ask your kind help, to…"