Brand new Monster blinks green continously and fan doesn't run

[JoFreak]

Hi,
I tried my brand new Mamba Monster today.
Got it a few days ago, soldered battery connectors to it yesterday and wanted to try it for it's first time today.
But it doesn't seem to work, as soon as I switch it on it starts to blink green.
The fan won't start which it does on my other Monster (and both MMP).
No beep sounds either.
And I can't get it to calibrate.
I can connect it to my PC with the castle link, I can change settings and I can update the software.

I use it in combination with a Spektrum SR3100, but the receiver/transmitter settings used, are the same settings that work with my other SR3100/Monster and both SR3250/MMP combos.
Batteries are 2S LiPo, Motor is CC1512 1800kV.

Do I have to send it in or is there a specific software version I should try first or is there a detail I just overlooked?