How do i send my BTC from a cold key?:
You cut around the hologram on the back with a sharp knife and pry it open (making sure not to scratch the QR code underneath). The QR code contains the private key which you can sweep with Ballet Wallet/Coinomi/Mycelium/etc.
can someone explain me step by step how to get the funds transferred from the coldkey cards with the ballet wallet app?
the app does not accept the qr code/priv key...
You cant use the ballet app if you dont have a ballet wallet to seep the funds. The coinomi app worked best for me.