I wouldnt recommend forcing the pad under the battery door. If you look under there youll notice that the waterproofing works by letting the rubber gasket fall into a channel; if you add something thatll push the gasket away from the channel, it might be enough to let water in.
I actually just got my wireless charging pad for the Note 2 in the mail today. I'm planning to adapt it to my Xperia ZR but in a different way. I plan to put it between my phone and case, and connect it thru the docking connectors on the side of the phone. Ill update you with photos when im done if it comes out alright. Right now im just worried about how Im gonna get it to sit right without covering the flash.
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