Why won't the earpiece for my iPhone 5s work?

I found and downloaded a schematic of the phone 5s, and thanks to some helpful comments by others answering someone who had a similar question I was able to check two resistors, labelled FL51 and FL52 on the schematic, to see if the problem was on the logic board. The resistors seemed fine upon visual inspection and when I checked the connection between those two resistors and the corresponding pins on the connector, continuity was detected. Next I switched the touchscreen from my brother’s iPhone 5s with this one and when I made a call the earpiece worked, so that confirmed to me that the problem was either in the earpiece receiver that came with the replacement touchscreen I bought or somewhere along the connection to it. I was going to switch the earpiece receivers from both touchscreens to see if simply replacing the earpiece alone would solve the problem, however while removing the replacement touchscreen I dropped and cracked it, so I bought another touchscreen and the earpiece now works.