Don't give up just yet - it's always difficult typing suggestions when instinctively if the kit was infront of you you would just do things!
Do you have a servo tester?
Do a visual check of the 3 pin rc plug on the esc - pins look ok / seated correctly/ haven't pushed themselves out of the back of the plastic plug?
Just to confirm are you using the throttle channel on the receiver?
What is the model number of the Spektrum receiver?