1 Answer

How to unlock a Whirlpool Duet dryer according to its manual:

Unlocking
Unlocking will occur only under the following conditions:
1. The drive motor speed equals 0 or the time since the drive motor STOP command has
been sent to the Motor Control Unit is greater than 180 seconds.
2. The time since the inlet valve was CLOSED is greater than five (5) seconds.
3. If the temperature of the water is greater than 122°F (50° C), the water will be drained
before unlocking will occur.
4. If the water level is higher than the wash level in the Delicate, Wool or Handwash cycles,
the water will be drained before unlocking will occur.

The Unlocking Routine is:
1. The Door Unlock Relay is energized for 40 ms.
2. During the next three (3) seconds, the contacts of the Door Lock are checked.  If the contacts are OPEN, the Unlocking Routine is finished.
3. If the contacts are still CLOSED after three (3) seconds, the Central Control Unit energizes the Door Unlock Relay for 40 ms. and then check the door lock contacts for three (3)
seconds.  If the door is not unlocked after 6 trials, the Central Control Unit will enter a
failure mode and the digital display will show FdU.

For more information you may go to the following links where guides for the dryer can be found:
https://secured.whirlpool.com/Service/SrvTechAdm.nsf/2cd44500d572193285256a45004fd9d6/eab852a13fbc842085256aa200643dd6/$FILE/Duet%20Job%20Aid.pdf, and 
http://dl.owneriq.net/0/00a2db78-f76d-47cb-b2ae-68e4d85770fc.pdf.