@Jan_Belak, you need to fix your soldering joints, they mustn’t be connected with solder blobs.
Take your soldering iron, reheat the soldering points (turn off your MAKERbuino before soldering, this is VERY important), the excess solder will stick to your soldering iron’s tip and you can just wipe your soldering iron in a wet sponge.
You can also unbridge the soldering joints by pulling your soldering iron between two bridged pins.
Pay close attention to the tips given in build guide’s chapter #3:
Especially this photo:
Yes, it should work after you fix it, that is the definition of the word “fix” I think…