For the past 4 days my phone is acting up. First I could not find a signal at all! Even if it reached 1 bar, I could not call out. I would hit dial and as soon as it began to ring it would hang up instantly. Took 10 minutes before I could call out. Then it started randomly shutting off 3 days ago. I plugged in to charge it and it shows 50-80% charged majority of the time but still shuts off. I installed the update 2 days ago to see if it would help but the notification still pops up to update. Now the phone will not stay on more than 5 minutes unless you plug it up. Should I replace the battery or the phone?