1. All events we know of are either caused by other preceding events, or are random.
2. One could reasonably claim that all events can ultimately be traced through their causal lineage to a random event, be it a random motion of a particle, the primordial quantum fluctuation that led to the universe, or subsequent fluctuations that broke the "smoothness" (symmetry) of the expanding universe and gave it detail.
3. For free will to exist, we have to posit another primary origin of events -- we don't know whether it's a particle, a field or some other entity and we can apply whatever label we want to it, but it will necessarily be another primary origin of events alongside random fluctuations.
4. If we disallow (3) as too "spooky", then what we're left with is the idea that what we perceive as free will and/or consciousness is an epiphenomenon that arises around randomness, especially randomness in large complex structures of connected, interacting nodes such as neurons.