Havent read the thread ok? But one of the reasons IMO the OP is having the problem is because he might need to have the cleats (or the feet, depending how you look at the problem) in another (wrong) angle. The feet to unclip needs like 5 to 8 degrees. If the feet is clipped in a position where the feet is like in 4 degrees you can't twist the feet enough to release the pedal. As direct consequence, it feels like is too hard too unclip or you cant unclip at all.

The feet twisting movement is too short, the only way to fix that is to angle the cleat a tiny bit so the heel is closer to the frame, hope you got the idea, is just a tiny bit like 1 or 2 degrees, you have to test.

But since I havent used spds ever, I can't tell you if you can change the angle of the cleats a tiny bit or not. My understanding is that the SPDs cleats have a fixed position in the shoe.

Hope this helps.