Door popped open and now is locked and will not unlock

Check the heater coil for opens or shorts.

those have a 2 latch system, sounds like the second latch that engages during the spin cycle never quite completed the safety lock , you could try and jumper the latch to see if that would release it, But it seems the secondary latch wasn't working properly in the first place, even the heaviest loads shouldn't pop the door open,

Because of the high spin speeds of front load washers, the doors are equipped with a latch and lock mechanism to prevent the door from being opened during the washers operation. These locks will often be actuated by a solenoid or wax motor to ensure they remain latched during the wash cycle. This model uses a two stage lock that latches the door when the load starts, and then when it is time to spin, the second lock engages to ensure the door is properly secured prior to beginning the spin. When this second lock engages, it also closes a set of switch contacts (the auxiliary door switch) telling the control board the door is closed and locked. If for some reason this switch is not closed, the washer will tumble during what would normally be the spin cycle until the entire cycle is complete.

Hi,
Make sure you are allowing the washer to completely finish its cycle before opening the door. It is normal for the door to lock at the end of a cycle. The locking mechanism keeps owners from opening the door before all of the water has been drained. If the door on the washer is locked, select the "Drain" or "Spin" options on the front-load washer. This will completely drain the water from the system and unlock the door, allowing you to open it.

Please see the following Whirlpool / Maytag service manual for Neptune washers.
https://secured.whirlpool.com/Service/SrvTechAdm.nsf/2cd44500d572193285256a45004fd9d6/dc59d905140253e18525729c005765f4/$FILE/Maytag_Neptune_Washer.pdf

On page 3-1 the manual explains that if the washer shuts off during the spin cycle, the problem points to a weak spring in the door lock mechanism.

"Shuts OFF In The Middle Of The Spin Cycle:
During the spin cycle, the machine control
monitors the door lock mechanism to ensure
the door is locked. This is done through the
door lock enable switch. During "lock mode,"
the shaft of the door lock mechanism is
pressed forward by the door lock wax motor,
and the shaft presses in the button of the door
lock enable switch. If the machine control
board sees the switch OPEN during the spin
cycle, the machine control board will automatically
shut the washer OFF. This is caused
by a weak spring in the door lock wax motor.
Replace the complete door lock mechanism.

1. Driver's doo opend and unlocked, all other doors closed and locked
2. Inser Your key in ignition, don not turn, remove key
3. using the manual lock/unlock button on ther dirvers door, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times)
4. Shut door
5 Open door
6. Using the lock/unlock button on the direvers door, slowly press and unlock 5 times (count the lock 5 times and the unlock 5 times)
7. With the door open insert you key into the ignition, turn to ON position (don't start), wait 5 seconds. Trun off and remove key.
8. Locks should cycle once (Car will lock and unlock once). If they don't cycle or they cycle more that once, do stips 1-7 over.
9. Using the remote, push lock button, hold for 1 second, release. The locks should cycle once. If not start over and go slower.
10 Close the door. Open the door. Press the lock button on the remote. The locks should cycle. Close the door. Press the lock button on the remote, the doors should lock. Press again and the doors shoud unlock.

I got this from a site called FixYa (don't have URL). It took me a few tries but it worked like a charm.

take the kickplate of the machine of and put your hand iside by the door lock , fill a round tab there just pull and the door is going to unlock

1. sitting in driver seat, with driver's door OPEN, press lock/unlock button ON THE DRIVERS DOOR to lock all doors, then manually unlock driver door only.
2. Insert YOUR key in ignition, DO NOT TURN, then remove key.
3. Using the same lock/unlock button ON THE DRIVERS DOOR, slowly press lock-unlock in 5 cycles
4. Shut door.
5. Open door.
6. Using the same lock/unlock button ON THE DRIVERS DOOR, again slowly press lock-unlock in 5 cycles
7. With the door open insert your key into the ignition, turn to 'on' position (DON'T START), wait 5 seconds. Turn off and remove key.
8. Locks should cycle once (Car will lock and then unlock once by herself). If they don't cycle or they cycle more than once, do steps 1-7 over.
9. Now using the remote, push lock button, hold for one second, then release the button. The locks should cycle once. If not, start over and go slower.
10. Close the door.
11. Open the door.
12. Press the lock button on the remote. The locks should do a lock-unlock cycle.
13. Close the door
14. Press the lock button on the remote, the doors should lock.
15. Press unlock button and the doors should unlock.

1. sitting in driver seat, with driver's door OPEN, press lock/unlock button ON THE DRIVERS DOOR to lock all doors, then manually unlock driver door only.
2. Insert YOUR key in ignition, DO NOT TURN, then remove key.
3. Using the same lock/unlock button ON THE DRIVERS DOOR, slowly press lock-unlock in 5 cycles
4. Shut door.
5. Open door.
6. Using the same lock/unlock button ON THE DRIVERS DOOR, again slowly press lock-unlock in 5 cycles
7. With the door open insert your key into the ignition, turn to 'on' position (DON'T START), wait 5 seconds. Turn off and remove key.
8. Locks should cycle once (Car will lock and then unlock once by herself). If they don't cycle or they cycle more than once, do steps 1-7 over.
9. Now using the remote, push lock button, hold for one second, then release the button. The locks should cycle once. If not, start over and go slower.
10. Close the door.
11. Open the door.
12. Press the lock button on the remote. The locks should do a lock-unlock cycle.
13. Close the door
14. Press the lock button on the remote, the doors should lock.
15. Press unlock button and the doors should unlock.

Long beep to follow if successful.

Remote Programming Instructions

1. Driver's door OPEN and unlocked, all other doors closed and locked.

2. Insert YOUR key in ignition, DO NOT TURN, remove key.

3. Using the MANUAL lock/unlock button ON THE DRIVERS DOOR, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times).

4. Shut door.

5. Open door.

6. Using the lock/unlock button ON THE DRIVERS DOOR, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times).

7. With the door open insert your key into the ignition, turn to on position (DON'T START), wait 5 seconds. Turn off and remove key.

8. Locks should cycle once (Car will lock and then unlock once). If they don't cycle or they cycle more than once, do steps 1-7 over.

9. Now using the remote, push lock button, hold for one second,
release. The locks should cycle once. If not, start over and go slower.

10. Close the door. Open the door. Press the lock button on the remote. The locks should cycle. Close the door. Press the lock button on the remote, the doors should lock. Press again and the doors should unlock.