I think Greg is missing the final boss 
. For example the materials of the top get Greg matter 
, push in Fusion Reactor Mk3 
. Serve energiyu and get the portal 
. Go to the very Ultimate Battery 
(this is the pass 
). There boss Gregorius 
. After killing 
the boss get completely full Ultimate Battery 
. And cheers, Greg passed completely 
. That's such nonsense, I guess 
.