Do you know if at any point the sump overflowed on to the driver, this is the most common cause of new pump failures. The drivers were not mounted, some maintanence is done and a bit of water enters the driver and shorts it out. Wet hands can also be a culprit. I would suggest swapping the drivers, the manual shows you how to open the drivers and disconnect the pumps, make sure the power is off and see if the pump fires up on the new driver, if it does and the driver was not damaged by water it would be covered under warranty.