My Support is frozen or stuck in the open position.Updated 2 years ago

If the supports don't seem to want to move you may have what they call a static seal. What you would need to do is install one lift support at a time and very carefully open and close the hatch and then install the 2nd one and do the same, just be careful to close the hatch very slowly with the one support so as not to bend or warp the lid. 

Note that most Lift Supports will NOT compress without being installed on the application.  They need the leverage provided by the application that is not reproducible simply by applying hand pressure.