Recover from failed upload

#1

According to the documentation I need to compile a version to inlcude the FrSky telemetry. I installed the Cygwin Toolchain and issued make px4fmu -v3_default to build for a Pixhawk mRho clone board. I then used QGroundcontrol to flash the generated .px4 file. The upload failed and now the board is not responding. I could use some advice on how to recover from this.

#2

I was finally able to recover the board in QGroundcontrol and load a stable version.