I would suggest starting by spraying the hinges with a good lube,and then taking a SOFT pine block and a hammer,and GENTLY tapping it to break the windshield loose.
The idea here is to use vibrations to break the seal,not brute force.
Once it moves even a eighth of an inch,lube the hinges again as well with spray lube to lube up the new opening as far as possible,and then take the same SOFT wooden block and hammer and GENTLY tap is closed again.
If you are having trouble,you can try taking a razor knife and cutting the rubber away from the windshield frame to make it easier.
When you have done that,tap it open again.
"Patience" and "gently" are the two keywords here. This ain't a contest,and it doesn't even have to be finished today.
Repeat until it opens all the way.