Yes the USB midi also power the PreenFM.
The Led is currently not used.
Initial test:
. Do the led of the LCD turn on when the PreenFM is power up ?
. Display : have you tried to turn the LCD contrast resistor to the 2 extreme position ?
. Did you remove jm3 after having flashed the firmware ? jmp3 force the PreenFM2 to boot in DFU mode.
. Double check the command you used to flash the bootloader and firmware and do it again. Did you run the command from the zip file ?
To check if the bootlader is correctly flashed.
. see
http://ixox.fr/preenfm2/manual/upgrade-firmware/ . Open Jmp3. power up the PreenFM while pressing button 3. You should see the device on your computer exactly as if Jm3 is closed.
To Activate USB midi without display, download the attached "settings.pfm" and copy it on your USB stick in "/pfm2/" folder.
But you should hear sound when sending notes to Din5 input any way.
Let me know how it goes,
If no progress, i'll upload a picture to check the ground, 3.3V and 5V on the PCB.
Xavier