Professor Ivo's nanotechnology-based robot A.M.A.Z.O. was able to get everyone's powers by changing its own underlying material structure. That's fine in most of cases, but Green Lantern's powers aren't based on quantum structure of the ring. It needs to be recharged with a Lantern which is connected with the Will Power bank on Oa.
How on Earth did he get access to the Will Power without recharge? Even Green Lantern's ring can't directly access that. It needs to be recharged.