Samsung Galaxy 111 Battery problem HELP PLEASE

[Elgin]

It could be a problem with email synchronisation https://www.youtube.com/watch?v=0L-7Y0Zz2po

[sunflowers]

I have a Galaxy 111. A few days ago the battery started suddenly to drain within a few hours of being fully charged, even without using it. I put a new battery in but it was still the same. Went to the Vodafone shop who said it could be a virus and reset it to factory settings. Guess what, still no improvement!
Does anybody have any ideas please?  I can have it fully charged last thing at night and by morning it's totally flat and switched off.