You actually don't need any special tools to open a screw on back. There should be special grooves on the back indicating that it's screw on instead of pop on. I use a pair of needle nose pliers ! Using the needle nose pliers straight up and down on top of the case,put the tips into the groves on either sides. Be careful to not scratch by slipping! U can use a thin peace of cloth over the back while doing this for a little protection. But that has always worked for me. Depending on how tight it's on May need quite a bit of force to break it free. I hope this helps ! Good luck ...

There could be a few different reasons it won't charge. I know for one my HTC seems to be picky with charging cords. Also use a flashlight and check out the charging port for dirt or debris and broken parts in there. Good luck .

Actually you don't have to get the battery powered case to get a more powerful battery for your phone! I haven't checked for this particular model yet but I know you if you look on eBay for replacement batteries for cell phones they almost always offer a more powerful same size,for the phone. But honestly if it's shutting itself down at 25% then there maybe be more of an issue then just with the battery. Also check your settings thoroughly too before going through replacement! Just incase there's a power saving mode that's set to $@$*!& off at that percentage. Still seems like it would warn you tho! Good luck!