After repairing a Nexus 5x LCD/Digi I am not able to get audio out of the earpiece speaker. I can briefly get audio on...

Looks like Parts4repair has them

make sure you solder the IC chips onto the new LCD/Digi. without that flex cable soldered onto the new display, the power button won't work. It can be a little picky. If you already soldered it, try reworking it with a little bit more solder on the pads.