Board problem? Rapid flashing red LED

[Steve_Elves]

I suspect I am forgetting something very simple.
Z-Uno 2 Rev. 6, connected to COM 9, all seems fine. Compile and download Blink example sketch, no errors.
Red LED flashing rapidly, no errors shown in Serial monitor (no other serial communication in the sketch in any case).
Bad board, or something incredibly stupid on my part?

[Steve_Elves]

My board is Z-Uno2 Rev. 6. I notice that the firmware seems to be for Rev. 7 now. The picture of the board in the documentation is a little different from my board as well - no socket for a battery connection, perhaps? Where can I find Rev. 6 firmware?