Solution for Non Charging Nexus 7 with Red Exclamation Mark.

My sister now uses my old 2012 nexus 7 which up to lately has had no problems. She came to me the other day saying that it doesn't charge any more and decides on a day to day basis whether it will switch on or not. It showed the battery icon always with a red exclamation mark, never charging, never changing.

I used some of my usual tricks like wiping it, and some ideas offered up by the internet. Nothing worked until I stumbled across someone who had opened there's up and found the battery wasn't fully plugged in. So I thought I would share how easy this is to do and save someone the time sending it back to Asus or hiding it in a draw. First I turned off the device, and found that the back easily came off with the use of a pen knife. Just gently slide under where the back meets the side. Once it's open a little run your nails along the gap and pop it open. I found a video here just for referencing. 
When it's open make sure you have a good look around, it's not very often you get to see what's inside your device. In the picture below I have circled the problem area. This is where the battery connects to the nexus. In my picture there is a piece of tape that runs over this plug to keep it in place. On my sisters nexus, this piece of tape was not present  I found on hers that the plug wasn't pushed all the way in. This was definitely the cause of the problem.
While the back was off I restarted the device just to make sure it was fixed. It was so I put the back back on!Hope this saves somebody time and effort. If you did find this useful please +1 and share, also don't forget to check out the rest of my blog.