how do i make a regular chocolate syrup get solid?
You'll have to get it pretty cold to get it to freeze. Due to freezing point depression, all of the dissolved sugar in that syrup will give it a freezing point of well below 32F. There are a variety of freezing point calculators available online, most of which probably call for more chemical knowledge of the solution that is available. I can find one source claiming that simple syrup freezes at around 18F though.