I like Origin Jazz but he's another tightly packed, clear plastic (tabs) bundle in vehicle mode.

Going back to robot mode by reversing the steps is impossible. The last step (#19) locks the doors in place. So my method, which also puts less stress on the roof clear tabs, is to angle the arms down, then gentlly wriggle and split the legs horizontally at the spoiler, then the legs can be pulled out a bit and the doors unlatched.