Help reparing Sony WH-1000XM3

[DavrosTheDalek]

Hi all,
I need some help repairing my Sony headphones. Symptoms: Doesn't charge when USB is plugged in. USB cable also not recognized (would normally switch off when plugged in). Charger light does not light up.

My suspicion is that a chip on the USB connector board has given up the ghost. I see the 5V USB power next to it, but I don't see any voltage > 0.5V on the connector to the rest of the headphone. Problem is, I am not sure what chip that is. 
It's a 2x2 mm square, some contacts below the IC, can't tell how many. Seems to be labeled 04/A  (or 047a) and 9M92. I don't recognize the logo, if it's actually a logo and not just the pin1 indicator
I'll attach a picture here.
The resistor below it is 100k, the one to the right is 5k. The soldering pad above it has 5V USB, the one to the right is GND. My suspicion is that the area to the lower left should get connected to the 5V (or should have some reduced voltage, but I doubt it, there is a li-ion in the system with 3.7V).

Any ideas?
Thank you all in advance!
 

[DavrosTheDalek]

Ok, found out some stuff.
I mechanically remove the IC. It's a 2x2mm BGA. Most of the connections go to the connector side V_BUS. One goes to GND, 2 go to V_out and one goes to V_ouit via a 100kOhm resistor.

Is that some reverse polarity/current protection with some clever MOSFET hookup? Or some ESD protection or over voltage protection?

I tried just bridging V_BUS to V_OUT, and the headphones charge again.