It's amazing how freak things like this can happen, and they do happen all of the time, so don't beat yourself up over it too much.
It's good that he's eating and moving around normally because that may rule out a serious head injury, but you need to be very observant of him for the next week or so, and if you see any signs or symptoms of a neurological issue then he needs to go to an experienced reptile vet asap. Look for disorientation, falling over, flipping onto his back, vomiting, lack of appetite, excessive sleeping, etc. These are all signs of concussion and possibly a more serious brain injury, and that would require vet care immediately.
As far as his eye goes, I've always approached pet injuries (as well as my own) with the idea that you don't want to mess around with the eyes, the ears, or the hands (hands apply to people obviously), because these are the organs that are most important to basic daily life and basic life functions, and if a living creature loses their sight or hearing it can be detrimental to their quality of life. Plus, once an eye is injured and the sight is compromised, it's usually not reversible. So I'd say that if he doesn't start keeping that eye open in the next day or two, you need to get him to an experienced certified Reptile vet ASAP to get his eye checked out. The fact that he's keeping it closed indicates that this is where the phone hit him, and he may be keeping the eye closed for a number of reasons, including swelling (this should resolve itself pretty quickly), an injury to the eyeball itself and the light is hurting the eye when its open (more serious and won't resolve itself quickly), etc. So you don't want to mess around with an eye injury if he doesn't start keeping it open soon.