With small hex hardware like this, if you try to pull it out and it won’t rotate, the last thing you should do is push even harder.
I really do think these should come with an instruction manual, and in this manual I would have written
“On the star plate adapter, when removing the three flat head hex bolts, make sure to heat them up thoroughly with a blowtorch before trying to remove them”
@Boardnamics Is already working on a way to prevent this in the future with a new design