It feels like the brakes are on?
A hydrostatic will move with the brakes locked but it squeals like a stuck pig. I have to assume that the pedals are in the up position and the brake lock lever is not in the forward position. If this is the case, the brakes are not "on" and whatever the problem you are having is not brake related unless it has been sitting in four feet of salt water for a period of time, for instance, or are locked at the wheels with frozen fresh water.
Can you describe what your machine is doing. Is it a problem moving or is it noise?
There is plenty of experience here but more information is needed for anyone to help. Try again.