Hello, this is my first time dealing with android Samsung phone. Several days ago, I got up to a dead Note 3. I didn’t use it for anything but it just turned out to be dead after a full charge overnight. I went in to see what was consuming the battery the most and it reported Cell Standby. Is this a bad battery? I'll try to replace a new battery from mpj later.

Friend, I don't know what you are saying, you mean your phone is dead now ? bricked or its just discharging very fast ?

It could be anything, may be some application is causing excessive battery usage. Lately it was also discovered that some application had BITCOIN miners hidden in them, so you may try to reset your phone and remove all programs or you may install software like https://play.google.com/store/apps/d...sfeng.greenify, it may help you to figure out what app has been causing issue.