What to do if the trolley has been driven into water:

Immediately turn off the trolley, pull out the plugs, put the wheels in freewheel and continue pushing.
Switch off the remote control and do not use it.
When you get home, take the battery off and let it dry well
There is probably water in the thick tube. There is also the heart of the trolley. That water has to get out quickly, because when it dries, condensation forms and the drops are so small that it settles in the heart and breaks the circuit boards. This is only possible by pulling out the motor on one side. At the bottom of the thick tube there are 2 screws on the left and right. Unscrew 2 screws on the left or right with a torx screwdriver. Then pull the motor out. That is probably very stiff and is easier to put on the wheel and pull the wheel. Do not pull the engine out completely with a jerk, but when it is almost out it is easier. Carefully continue and then disconnect the electrical wires first. Then drain the water, do not return the engine, but let it dry for a few days. Reset the motor, tighten the screws and try the trolley again. Fortunately it did not happen often, of the 3x I had to renew 1 trolley the heart and 2x there was nothing wrong.