Is throttle plugged into the correct receiver port and the right way around? Also check there is no exposed metal on the bullet connectors between motor and ESC if you are using them. Any short there will kill the ESC.
Have you calibrated the ESC?
You need to get into the app and see what your switches are set to. It sounds like the throttle is on the flight mode channel, you want it plugged into channel 1 not channel 5 and the switch set to channel 5 not channel 1!
Apparently the last time I plugged in the esc I wasn't paying attention. It was plugged into #5 instead of #1. Plugged back into #1 and I now have proper throttle control. Still looking forward to checking out the setup with the app.
See, simple solutions are the best solutions. I have made all those silly errors myself.
Glad it’s all fixed! You will want to talk to the RX to set up your dual rates and expo before you fly anyway, so that cable won’t be wasted.