After SW downgrade to 3.08 and IMU re-calibration slow red and green flashing appears. There is no explanation for this is the manual. What does it mean? I don't dare to take off.,

Have you switched to NAZA mode ?
The NAZA LED sequence is different to the ones in Phantom mode.

Could you please be more precise. Does it go red, green, red, green... Have you got 6+ sats?

Here is the NAZA-M LED indicator diagramm

markus2015 Posted at 2015-2-23 03:18
Could you please be more precise. Does it go red, green, red, green... Have you got 6+ sats?

Here i ...

Thank you, yes it goes red-green-red-green...etc. Could it be "<7 sats"?

Perhaps you should look at the lights differently.  Look at it as Red...Green.... Red....Green

yes, red/green alternating is very normal for exactly 6 sats in s1top (gps mode)