Need more info, what was the "technicians diagnosis"?

You would only have an element if your model had sanitize as an option and actually raised the temperature of the water.

Is the "blinking" you mention the countdown time or is it a fault code? F (something) (normally a number)
I would check your pulley in the back of the unit to make sure its tight, remove entire back panel and look for large silver circle, you can also turn the drum by hand slowly at this time to see if you can duplicate the sound, it may be in the rear bearing, which is just an annoyance right now but could overheat and cause a leak, that bearing can only be replaced as part of the complete rear tub assembly ( CODE WORDS< VERY LARGE JOB)

The door not unlocking I think is unrelevant because unplugging the unit has stopped the cycle, not always releasing the door latch.