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Hi, you get a two year warranty, I would contact LG direct to see about a repair, the manufacturer has a lot more leway when it comes to repairs, if the phone is damaged in any way Vodafone are not allowed to repair it without repairing the damage first.
Back everything up as the first thing they will probably do is wipe the phone and reinstall the firmware.
I would certainly support the advice to approach the manufacturer via their online uk support site.
The thing I prefer with Apple is that if its in warranty there's no messing around sending it off etc. If warranted they swap it out in store. If out of warranty an express replacement can be bought.
I think the advice I received on here was wrong as the LG website states the warranty on an LG G3 is 12 months not 24.
Same issue with mine, had it since August 2014 and this week it just started hanging on the LG Lifes Good Screen. I tried different batteries including the one from my wifes still working G3 and nothing helped.
I managed to get into the phone eventually using LG PC Suite and saw there was an M software update.
As the reliability didn't seem to be possible to be any worse I installed Android M. Since then it has been 99% stuck on boot loop, although I occasionally get in long enough to back up some apps and do a factory reset.
However none of this results in having a phone that is useable in anyway shape or form. Currently having to rely on my old flakey and cracked Galaxy S3 as I need a phone.
The vodafone website definately says there is a 2 yr warranty on non-apple devices so will be contacting them I think.
Phone just back after being repaired under 2 yr Vodafone warranty. They've replaced the motherboard (though possibly just for SD card reader problem) and reflashed the rom as you'd expect. Back down to Lollipop again with no update to Android 6 available, but at least its working (fingers crossed)
Don't you think the issue with the phone could be hardware related? I experienced same issue and i tried flashing in a new rom. I literally followed all the flashing instructions i could find online but all to no avail.
However, loosening all the screws on the phone and re-screwing them back with emphasizes on the camera region, fixed it.
Credit goes to this page for the information.