No audio on speaker [board level repair]
Hi! So I have this iphone 6 that came in for tristar replacement (typical symptoms, died after being used on a car charger), after tristar I had to replace PMIC because it had an internal short on the 1V2_SDRAM line (I found it dicking around the rear cam FPC) Everything was working fine at this point. The day after I gave it back the client tells me he can't play whatsapp voice messages but before he was making phone calls and it was ok so I know audio worked before.
Now with the phone back in my hands, mics work, earpiece works, and headphones work, but whenever it tries to play audio through the loudspeaker it freezes for a few seconds, nothing happens and then it gives you back control (like it tries to access the speaker but it can't so the cpu locks up until it times out)
Long story long, what I have ruled out is:
-Parts (obviously), charge port flex, loudspeaker, housing shorting smth, etc.
-Software, fresh installed ios 11
-Audio codec IC, first reflowed, then reballed, then replaced it, nothing changed
-Power lines to the Audio IC, every line is fine
-Speaker Amp IC, reflowed then replaced, also power lines to this chip are fine
-CPU to speaker amp IC enable signal, can't remember the exact net name, but it is present when I try to play some audio through the speaker.
This is definetely a rabbit hole, and I've been dicking around with it for a whole week and not much progress.
-Also compared to a known-good board every diode mode measurement I felt was relevant, nothing came suspicious
Has anybody seen anything similar or can point out somewhere I may have overlooked? At this point I'm out of ideas really
If you read till this point: thanks in advance!!