Battery drainage/phone switching off

[AC Question]

Hi everyone, I've had this phone since Christmas 2015. But these past couple of months (I'd probably say since November) my battery has either been draining while plugged in. Or it will drain, charge slowly and then go from 37% to 100% in 2 seconds. I've also encountered the phone shutting off when its at 30%. Try to turn it back on and its saying I have 0%. I've also found that when it says that its fully charged, I wake up to find that its drained even though it's been plugged in. I've tried my absolute best to take care of this phone, but I just don't know what to do. Would resetting it help? Is this a virus? or is my battery dead?

 

[s_baig]

Unfortunately, your battery's life is over.. I am facing almost exactly the same problem and the technician suggested me to change the battery. So, I hope that your problem is solved as soon as you change your battery.
Regards.