Second thing you want to do is check the voltage at the blue & green wires where they go down to the lower unit. Slide the rubber sleeves back to access the terminals and connect your meter to them without disconnecting them. Should show near battery voltage on green when in forward and on blue when in reverse. If you do not get the voltages, check all wiring. A common problem is the shift switch in the remote control ($$$$).

A bit of warning: Never allow battery voltage to get to both blue and green at the same time while running. Doing that puts it into forward and reverse at the same time. and will bust something.