Hi all,
I too has been facing the same issue from quite some time. I own a Lumia 920.
In my case both the back button and home button activates automatically, eventually bringing everything to home screen, voice assistant comes up - tries to listen something, ends up saying "Call mummy or Open calender". And there is no way to disable the voice assistant, other than disabling it when locked. So this voice assistant comes up repeatedly and if you try to lock the phone to get rid of it, the funny thing happens - "Screenshots saved". Its irritating, cann't do anything with your phone. I tried restarting phone several times "volume down+power button", no use, i will be relieved for some time.
I was in the thought it might be some software issue, knowing about the AMBER update, i waited for its release. But the issue didn't fixed even after the update
Finally i visited Nokia care, i realized that my phone unpredictable behavior was better than Nokia care
Instead of investigating or observing or identifying the reason for it. They started complaining that the phone was already opened and touched up inside (blasted up my mind), hence warranty expired, only solution is replace with a new touch panel, which will cost 12K. And also confirmed that the phone's warranty is expired. For further reference i made a copy of the job sheet
With this response, i tried contacting Nokia through a different channel, Nokia care chat. They asked me to try restart (volume down+power button). the same know stuff again. Asked to hard reset the phone, i said i will try that after after back-up
I explained them also my experience at Nokia care centre, and was asked to check with some other nokia service centre and get back to us again with the new job sheet
Since there wasn't any track of the conversation, i mailed up Nokia care, with the issues and the already had chat conversation
Then i visited another Nokia care centre, this was again another interesting. The representative over there hasn't heard anything like that, hence they won't accept it for service or observation. Since after many phone restart's the issue comes up some time and remains for some time, my fate it didn't happened or occurred while i am at Nokia care. So no use reaching there. Even after saying about my prior conversation with Nokia care chat and asked to take the device for observation, the representative denied to do so
Finally I did a device back up and did a phone reset (settings->about phone->reset phone), even after that no betterment, issue happens randomly. Having to do nothing, using the device in vibrate mode all the time and phone locked if the voice assistant opens up
A mail chain was running and stuck now with Nokia Care regarding the same
If some one face the similar issue or any solution for this or better way to reach Nokia Care, please reply