Virus or remote control hack?

[Android Question]

Today my Galaxy Note II running 4.4.2 (last major update 2 weeks ago) starting acting highly unusual. When I turned the volume up, it would turn it back down - even when I wasn't touching it. This game went on for an hour. Then I shut down the phone, waited 2 minutes, and restarted it. A few minutes later, while sitting idle on the table, it restarted on its own (never done this before in 2-years). The volume up/down game continued. I took it to my local AT&T store, where we decided to reset to original factory spec. The volume up/down game continued for a another hour or so until ending (almost as if the remote controller gave up and went to sleep.) Then I spent the next 4-hours downloading a few apps, setting up 6 email accounts, and putting everything back together again. Do I have a virus or have I been hacked and someone has remote control?

 

[Hadron]

Neither is very likely at all. Indeed virus is strictly impossible: there is android malware, but you have to install it yourself (e.g. install a pirated app that has malware inserted into it). There are no true android viruses, i.e. self-propagating, self-installing malware.

A simpler explanation is that the button was malfunctioning (stuck or shorting).