my nexus 7 2012 has charging problems, it takes about bit more than a day (YES A DAY) to charge... its not software related cause I've tried everything software to fix. now, how can i pin point to which hardware is the problem? like an app of something which test the hardware. my main suspect is the usb charging port. but a part of me thinks it could be the motherboard or the battery(but it doesnt discharge to fast) it self. any advice? yes its a an old tablet. but it will be a good thing to do for a while. and nexus 7 with the right setup still kick butts.