Be extra careful when tightening down on the interposer. When I powered on upon completion, the battery was not connected. When I opened it back up, I saw that one of the little metal nubs holding the interposer in place had snapped off (the one on the side, not the corner). I was able to carefully tighten the wide head screw back in, watching the alignment, and the battery was successfully recognized. Hopefully the connection holds up.