I was able to extract the PCB by digging a small hole right next to the button (I used Blake's picture as reference). Just dig until you can see the small metal clip, push it down with a small tool and you should be able to slide the PCB right out of its case easily.
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=== Actualización (07/05/19) ===
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[image|1752860]
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Yes. I used a small drill, but was also considering using a soldering iron tip to melt the plastic and get to the clip. Whatever tool that can go through plastic should do the trick, just make sure you can reach the metal clip to push it.
I was able to extract the PCB by digging a small hole right next to the button (I used Blake's picture as reference). Just dig until you can see the small metal clip, push it down with a small tool and you should be able to slide the PCB right out of its case easily.