So, I've made an alternative fix and gonna stick with it.
The only problem there was basicly was that the turret only turned left but not right.
So with a friend a little more familiar with electronics we've measured everything we possibly could.
The problem wasn't in the button of the remote.
The problem wasn't in the motor of the turret.
The probelm wasn't in the wiring.
The pins on the main board just didn't get a current.
So, now we've switched the wires for tilting the barrel up and down (since there are 2 buttons for the same function) for the motor to the turret.
Result is I've got all the functions but when the turret turns the machine gun sound is also activated as well as the light on top.
Since I don't feel like buying a complete new mainboard I'm gonna stick with this configuration.
Next time I'll probably purchase a Heng Long
Thanks for the support!