Corrosion on new charger point

Argh, sorry about this, but I'm glad you're getting somewhere with it. Yes, I'll post an update soon warning people.

Hopefully you can clean them up a little more - maybe a mild abrasive like toothpaste, and then make sure you clean it off fully afterwards?

So what happens with the contacts is they're wired as follows, left-right in the pic above:

• GND
  
• ~10k pulldown to GND
  
• ~10k pullup to 3.3v
  
• Charge input (effectively slightkly pulled down to GND)
  
  

So I guess it's actually doing some kind of electrolysis - maybe even taking copper off the 'shiny' pin and depositing goop on the other pins. So ironically it's actually only the one shiny pin that you'd have to cover up and then everything would be fine.