MarkSetBot uses the Minn Kota Riptide PowerDrive (saltwater). Minn Kota provides the warranty on it and there are Minn Kota service centers all over the world.
Here is how you can find the one closest to you:
https://www.minnkotamotors.com/Authorized-Service-Providers
Before having it serviced, make sure you have tested the motor (the problem may be the ProNav): https://support.marksetbot.com/How-to-test-Minn-Kota-PowerDrive-V2-or-Riptide-PowerDrive