Cannot get any Arduino sketch to run

Hi,
I tried this with MacOs 10.11, with Win7, Win10 and Arduino IDE 1.6.7, 8 and 9
Board package is 2.9, Duo FW is 0.21.
Board Type set correctly, port available and selected correctly.
Opening any Duo Sample sketch and click upload.
Sketch compiles fine, led on Duo flickers, uploading progress ok.
Upload completes w/o error.
Duo reboots…
Sketch is NOT running. E.g blinking sample or RGB-Sample…no reaction…led blinks 500ms blue…as it does always
E.g BLE scan (with serial out)…no reaction.
Tried uploading FW. Put device in DFU. No matter if I use dfu-util or IDE…always get dfu suffix error.
Has anybody an idea ? Help

Do you mean the Arduino "DUE" ?

Moving you to that section anyway.

Bob.

ballscrewbob:
Do you mean the Arduino "DUE" ?

Might be a RedBear's STM32-based product, which is indeed named "Duo".

The info for this "Duo" board would also explain why using Arduino 1.6.x