I decided to get myself DJI NAZA for my quadcopter as almost everyone was raving about it.
I have self made MWC running Multiwii 2.0 on my quadcopter witch is running ok but I wanted better altitude hold and the videos in youtube show that NAZA is very good in doing that.

Received NAZA this week connected it to existing setup, connected to PC to set it up properly.
After plugging in the battery NAZA does selftest and the light goes off. When I try to arm the motors nothing is happening. I though that I was doing  something wrong so checked everything again couple times. Still the same… Motors would not arm.
So I started reading through rcgroups and apparently it happens with some ESC .
http://www.rcgroups.com/forums/showthread.php?t=1610564
There is even a list created which ESCs work and which don’t.
https://docs.google.com/spreadsheet/ccc?key=0Au16aK6Q-0p0dENkdXVGVHJLRm5fRTFQdjBZbUhxZ3c&pli=1#gid=0

Unfortunately I am using Turnigy Plush 30A and these are the ones that most of the time are working.
On the label mine are ver 3.1 I’ve bought them sometime in July 2011.


There is a workaround for this issue first you need to power up NAZA and then ESCs but I wanted a permanent fix. It seem to me that this is a software issue not hardware. So I opened up my Plush 30A ESCs to check what chip I have. I was lucky I had ATMEGA8L and that means, I will be able to flash SimonK firmware to it.
So used the following guide to flash one of them:
http://www.rcgroups.com/forums/showthread.php?t=1513678

After flashing connected NAZA and powered everything up. When I tried to arm motors, the one that was connected to flashed ECS started spinning the others were standing still. So I flashed the others and arming started working the way it was intended to.
Here is my Turnigy Plush 30A ESC with SimonK firmware in clear shrink tube.