If your lift starts and stops as you are raising or lowering the lift it is likely because the main battery level is on the verge of too low.
Our remote-control key fobs cut off and do not work if the main battery voltage is below 11.5 volts. To solve this, charge your main battery.
If you need to operate the boat lift before the main battery has time to charge, you can operate the boat lift with the manual Up/Down switches inside the power unit box. That switch does has a lower voltage cut off.
This should only be done to safely raise or lower your boat, do not continue to use the boat lift in this low voltage state.