Finally got it to work again.
I flashed this ROM using SP Flash Tool.https://mega.nz/#!wNcRFIoS!dD3d3KQlVMEW ... v55L6LVAHI
After flashing, everything worked except Calling/SMS/Mobile internet. Somehow the IMEIs got lost. (*#06# shows empty dialog)
I reset the (default, that the phone got shipped with) IMEI by using the build in "EngineeringMode" App.
You get into that typing *#*#3646633#*#* or simply searching the PlayStore for EngineeringMode App.
Under Telephony->GPRS you can set your IMEI, after pressing "Write IMEI", its important to reboot.
Now everything is working again.
I AM NOT RESPONSIBLE FOR ANY DAMAGE THAT IS CAUSED BY THIS TUTORIAL.
Even tho, in my opinions its pretty impossible to permanently brick MTK Phones.