Re: hit object, not sure what is wrong
The loud pop was probably the motor coming out of the motor lock down. I usually run my smaller motors with it unlatched except when running in reverse.
I do not understand what you mean by prop turns in gear, do you mean with or without the motor running? If you mean without then check your linkage to make sure it is going all the way into gear.
The indicator gets plugged easily with just 1 large grain of sand, try disconnecting the hose to it and then blow out the plastic fitting with compressed air.