[Humabout]

You only remain in geostationary orbit while you are in that orbit. As soon as you leave it, your some of your potential energy gets converted to kinetic energy via an increase in orbital speed. As you continue to force your speed lower, your orbit drops, increases orbital velocity, etc.

All of that said, you can thrust at an angle to affect a vertical landing, but it will burn a lot of fuel - enough to continually slow your orbital speed and keep your decent controlled -, requiring lots of dv equivalent, and, at the end, at least enough thrust to counter the pull of gravity.