The hammer must be all the way forward, before the thumbpiece can
be moved. The rear of the bolt is blocked by the hammer, unless it is
all the way forward.

A loose extractor nob, or rod, has nothing to do with moving the
bolt via the thumbpiece. A loose rod/nob will prevent the cylinder
from opening, but will not impeed the movement of the center pin.
The OP said the button does not move, so either the hammer is not
all the way forward, or the center pin is frozen in its travel path, or
as SP suggests, the locking pin in the extractor lug is stuck. If the
hammer will retreat, you can remove the side plate, remove the
hammer, and then tap the forward end of the bolt - the piece to
which the thumbpiece is attached. That might jar loose whatever is
hanging up the center pin.

Mike Priwer