Likely a bad motor control board
. Remove the front panel and check the board physically for signs of scorched components or blown fuse (non-replaceable). Maytag has improved the new boards and they come line-protected and with a new quieter motor. You'll find the Neptune manual here on the download section for reference on how to open the machine, etc. There's also a nice tech sheet in the top console which will explain the test procedures. Order a 12002039
for the kit. Instructions included.
Part # 12002039
Motor - Drve, AP4010145