I am trying to get a data backup from a broken LG/Google Nexus 5 smartphone. It was repeating in a boot loop, because the on-switch was stuck at always on. I dismantled the mainboard. Here is a overview:
After desoldering the little push button (from the sport marked with the arrow) I soldered two wires to the contacts the switch was shorting, to make a provisory switch. Then I reassembled the phone partially, to get it started.
While doing so I unfortunately pulled to much on one wire and ripped it off the PCB with the solder pad. Annoyingly it was not one of the four pads which are connected to the ground plane, but the "signal contact" which probably only has a narrow connection path to some controller pin.
As I can see on this microscope images, there is no conductive track leaving my broken signal pad on the top layer of the PCB. It is isolated all-around against the ground plane. So it must be connected by a "via in pad". Is that correct?
I already tried to cover the broken pad with tin by making a solder bridge between the neighboring ground pads, without success. But after the heating it gave me a better view on the underground of the broken pad.
I also tried to short the connection by a wire with an alligator clamp on ground on the one side and a multimeter probe on the other side. With the probe I tried to touch the via. I had no success in switching on the phone by this method.
Is the inner circular area with the golden point my target potential which I have to pull on ground?
- With what technique can I expose that area? Scratching?
- Are there some other spots on the PCB where I could search for my target potential?
- Is there an other way to get a data backup of the flash memory?
Thank you in advance!
Edit: You can find some close up photographies of the switch here: http://runawaybrainz.blogspot.com/2015/05/google-nexus-5-power-button-woes.html