Anywho, here's the transformation.
Stand it up using the usual Prime foot transformation
Remove the cargo bay. Extend legs. There's a cover around back that flips open the same as Prime had to conceal his head. It flips back here all the same to allow the arms to pass. Shift cockpit to one side and slide arm around to back. Twist cockpit the other way and repeat with other arm.
Cockpit down with both arms around back.
Arms swing to side. Chest panels flip in.
Chest panels slide in and lock onto cockpit concealing them little weapon pods. Arms down and fists out.