Welcome, I'm Chris (aka Moose) I'm an independent contractor here at Just Answer.
I do agree that there is nothing they would of messed with to diagnose and repair the speed control to effect the door lock. To me it appears like the door lock actuator motor is weak and to blame here. This is quite common on older vehicles. For example my mothers 08 Escape, she opened the liftgate then closed it, seconds later she needed back in for something and it would not work. I removed the trim inside, heated the actuator with my heat gun and it worked just enough to get the gate open to replace the actuator. Your actuator is mounted on the door latch inside the door. If you would like the testing or replacement steps let me know.
Thanks for asking your question and letting me try to help you.
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