Ideally what would happen is that your voter registration is assigned a block chain code and when you request your ballot, your block chain code is printed into the ballot paper, it is then scanned and recorded.  Problem is the machines are all different in every state and the data bases are maintained by the states so unless they were hacked it seems non feasible. But that is what block chain is, it records a transaction as it moves through the various stages of processing with a unique code with each step being sequential and attached to the original code, hence the 'chain'.  It highly effective but I just don't see how they bring it into the process.