Home Button - replaced; still not working

Home button was replaced professionally last summer due to liquid damage. The replacement button only worked for about 3 months. Thought I would try my hand at fixing it - after they diagnosed it a second time, saying they would replace the home button again for another $70. Spent this morning replacing the home button … still does not work. So perhaps the old button (hardware) was not the problem? What else could be wrong? It charges fine. And can be plugged into the computer with no issue.