DIAGNOSIS "dE" stands for "Door Error." It's similar to the three-beep issue but is the electronic version stored in the control board's memory. It means the dryer thinks the door is open when it's trying to run, or it detected a fault in the door switch circuit.
FIX First, try a hard reset. 1. Unplug the dryer from the wall outlet. 2. Wait for two full minutes. 3. While it's unplugged, open and close the door firmly a dozen times to work the latch mechanism. 4. Plug the dryer back in. The error should be cleared. Try starting a cycle.
IF THAT DIDN'T WORK The door switch itself might be intermittently failing. The hard reset clears the memory, but if the switch is bad, the error will come back. You'll need to test the door switch with a multimeter as described in the first question, and replace it if it's faulty.
HEADS UP Don't just ignore a dE error. If the door switch is malfunctioning, the dryer could potentially start with the door open, which is a significant safety hazard. Get it fixed.