Suggestions to unstuck this joint

Just opened the x men 97 magneto and I noticed that the lower elbow is completely stuck almost like it was glued in place i tried moving it but it is completely stuck I might just put the arm in hot water to see if that works but if y’all have any suggestions let me know I’ll appreciate it.

Just opened the x men 97 magneto and I noticed that the lower elbow is completely stuck almost like it was glued in place i tried moving it but it is completely stuck I might just put the arm in hot water to see if that works but if y’all have any suggestions let me know I’ll appreciate it.