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I spent some time today modding my 'brand-used' X12 Pro case with the Qi wireless charger taken from a bad E12 set.
The X12 & E12 have different circuit boards and retainers as the charging posts are aligned differently. You can't use an X12 in an E12 case and vise versa.
Once I had the cases apart I saw the circuit board had the input provision to for the wireless charger.
It was necessary to remove the original thicker double sided foam from between the battery and circuit board holder. That was replaced with 3m double sided foam, the automotive stuff that is grey. I actually stretch it so it's thinner as well.
To fit everything I filed the bottom of the cupped areas that the earbuds point down into for a little more room inside.
The Qi coil from the E12 also uses a thicker double sided black foam, which I replaced with the stretched grey 3m stuff as well. The E12 case has more room inside as the cups are not as deep. No idea why as the X12 is a much shallower fit.