As that was the question that I responded to. The primary can not be hacked by electronic means as there are no electronics to hack. Each precinct does balloting (we used post it notes, which suck for the purpose because they stick together. Sorry 3M...) and counting was done by multiple people to determine the nominee. From that point, delegates are chosen to go to the regional convention. At the regional convention (at least at mine) the nominee was chosen by people gathering in groups on the gym floor.
I haven't been to a state convention but I assume there are no balloting machines used there either. No machines means no electronic hacking possible. At the regional convention, you count legs and divide by two. The delegate themselves are the ballots. No machines (that I know of, that one lady was kind of stiff, but I think it was arthritis, not robotics)
The general election is different and uses machines to tabulate marks on a paper ballot. The ballots are retained and can be recounted. Each ballot is verified as it is fed into the machine. If it detects an overvote or unreadable ballot, it is spit back out for review. The 4 or so that occurred while I was working as an election judge, I think one was corrected and the other three were recorded as spoiled and the person given a new ballot and instructions to mark more carefully.
With our systems, jiggering the results would be a high risk thing. A recount that catches a systemic discrepancy would mean the end of the company that manufactured that machine.