[Galaxy Tab Pro 12.2, 10.1, 8.4 Q&A, Help & Trouble] VeinkWiles:
I just got this tablet (to replace the garbage SGH-I467) a few days ago (Thu., May 15th). For the first couple of days it worked like a dream. However, the last 4 nights/3 days, I have been encountering some strange issues. What I will do here is describe the issues I've been having, what I have done in attempts to fix them, list some of the things I think may have caused it, and include any additional info/questions.

Before all that though, I would like to mention that I am not a developer, but I am a bit 'tech savvy' and am more familiar with/knowledgeable of technology than the average user. Also, I have spoken with Samsung tech support and even had the support guy access my Tab Pro 12.2 remotely (I will explain what I learned from that below). So, without further ado (I apologize in advance for the long winded nature of this post, but I want detailed):

The Issues:

1) Screen "flickering"—By flickering I mean that it is shutting off and turning on rather rapidly and sporadically, though inconsistently.

I first encountered the problem 3 days ago (the 18th).

Four nights ago (the 17th), before going to bed, I plugged the device into the same outlet I have used for all my mobile devices, when I woke up (on the 18th) the screen was doing exactly what I described. I hit the home button a few times and it stopped.

That night (the 18th) I plugged it back in to the usual spot before going to bed. The next morning (yesterday, the 19th), the screen was "flickering" again. I tried to press the home key a few times, as well as both the soft keys, nothing. In between "flickers" you can see the lock screen, where I have to enter a pin, but even while visible I can't type anything. So this time, to try to solve the problem, I held the power button + volume up to get to recovery and wiped the cache partition, rebooted the device, and viola, it worked again. Thinking that I may have to factory reset the device if the problem persists, I used Kies to backup all my data. I used the tablet the rest of the day, even plugged it in (in a different outlet than the one next to my bed) for a while and had no issues.

Last night (the 19th) I did pretty much the same thing, but this time, thinking that it might be an issue with the device getting too much power (the Quick Start Guide says: "Note: Connecting the travel adapter improperly may cause serious damage to the device."), I used a travel adapter from one of my other, USB 2.0 devices (the only difference between the adapters is the output: 2.0 = 5.0V—2.0A vs. 3.0 = 5.3V—2.0A, and output was specifically what I was concerned with). This morning (the 20th) the problem has returned, but now includes my second issue: the hard home button and both soft keys, back and recent apps, no longer function. So I immediately tried to wipe the cache partition and reboot, but this time it didn't work. Thankfully I had anticipated this yesterday and had that Kies backup, so I wiped the entire device back to factory settings. But alas, it was unsuccessful and the problem persists, including the loss of button functionality, with the exception of the power and volume buttons.

It is important to note that when I first got the Tab Pro 12.2 and set up the lock screen, I used the option that delays the actual locking of the device 10 minutes after screen timeout, but set it so that if I lock the screen with the power button it ISN'T delayed and immediately locks. That being said, a couple of times when the "flickering" stopped long enough to momentarily use the device, I was able to enter my pin and unlock. But when the screen starts flickering again, it locks the device, so the power button must be affected as well. Though since the first factory reset of the device, I haven't set up a pin. I have done several factory resets and none of them have worked. The best result has simply been limited (no back, recent apps or home key) and momentary functionality. I tried using Kies to do emergency firmware recovery, but every time I click the option it disconnects the device.

When Samsung tech support remotely accessed by device (I used one of the momentary functionality windows to download the required application) the agent was able to utilized soft and home key functionality, even though I couldn't. This tells me that it was hardware related, not related to UI/software.

So there are a couple of things I think may have caused/contributed to the problem:

The first, which I vaguely touched on above, is the power issue. Perhaps I have shorted the device out somehow. The outlet I use to charge things while I'm sleeping is on the wall behind my bed, so I have to use a common extension cord, one that has 3 outlets at the end. I have a light plugged into that and in the past have charged both my SGH-I467 (AT&T Note 8.0) and my SGH-I747 (AT&T S4 Active) with that cord and outlet. That is the only place I have charged the SM-T900 overnight, but none of the other power sources I have used have caused these issues.

The second possibility is a virus some sort. I have never used the Samsung app store on any of my other devices, but in order to update the Hancom Office suite I had to. Since I had an enjoyable time using it to that end, I decided to see what else I could find on Samsung's store. I downloaded a couple of things (the "Official Captain America game" and a couple wallpaper/theme apps) and was looking around the store to see if there was anything else I wanted to download. I found several apps that had reviews claiming they were trojans, so I immediately checked the reviews for the apps I had downloaded, but none of them had similar reviews. However, that does not mean they didn't have viruses.

So, what do the resident Android gurus of XDA think about these issues?

I tried searching all over the forums and elsewhere online for people having the same issues, but couldn't find anything. Have any of you ever encountered something similar to this?

Until recently, I hadn't ever heard of anyone getting a virus on an Android device. Are they common? What is the nature of Android viruses?

If these issues do have something to do with overcharging/shorting the device, how can I mitigate that problem? Tonight when I charge the tablet, instead of using the USB 3.0 charging cable, I am going to try just using the 2.0 cable. As I understand it, that can be done by simply plugging it into the right side of the port. Hopefully that will stop exacerbating the problem.

Again, I apologize for such a long winded post. I would like to thank you all in advance. If ever I have problems with an Android, you guys are the ones to ask!

*UPDATE* Before I started typing this I was attempting to run the Kies 'Firmware Upgrade and Initialization', as opposed to 'Emergency Firmware Recovery', to see if that too would disconnect the device. Unfortunately it said that my device needed to be charged first. So I shut it down and plugged it into a surge protected strip and began typing this post. Occasionally I would go over an check the charge. While it was shut down and charging I was able to use the home key to bring up the green battery. Once the charge looked like it was about 75% complete I turned it back on and lo and behold, the "flickering" issue looks resolved and so does the button issue. I can go back, enter the recent apps and task manager, and use the home key functions. For how long this will last, however, is unknown. I guess we'll see in the morning. I'll post what happens tomorrow.