My suggestion would be take your batteries to an auto shop or battery place, so they could do a load test to the batteries. You may have 12 volts but no amps. If this doesn’t solve your problem, take the top half of your trolling motor off and look to see if you have some frayed wires or a loose connection inside. This happened to me once, while I was out at Chester Woods. I took the time to take it apart out there on the water. ( I was too lazy to row all the way back to the landing) Did you notice if the top of your trolling got hot when you were last using it? This is a good sign that you have an electrical problem inside your trolling motor. You need very heavy gauge wire to carry the current needed to run that 12 volt motor. This is why they tell you not to run your trolling motor out of the water. The motor can get very hot and burn up inside.
Good luck ! ! ! !
VC-13 Mike