@drennanelawar Luckily this one was a spare. Unfortunatly after updating to 16.04 back to square one. Also now have OnePlus One but mainly for the battery life.
Edit 24/07
Have the nexus running again on 16.04 so far all ok after 14 hours and three restarts. On/Off button is now really sensitive after all the bashing. Also had to turn of all vibrations as that seemed to keep bringing up restart, switch off etc dialog box.
Now also think the low battery charge was not helping (15% approx.) when I got it going, with the boot loop. Have had no issues since charge got above 30-40% with startup.