Samsung Galaxy S3 dying and jelly bean update predicament

i had my s3 fixed up from being dead a while back now it wont update and just show no updates available in OTA . i also tried doing it via KIES but it also shows that your device is not supported to update via KIES . i tried it many times and did everything possible .

my battery percentage also gets stuck to some percent and then when i connect the charger or after some time , it drops down rapidly .

help mee :'(

Have u rooted your phone? If u have Kies becomes useless in terms of updating your firmware/software...

Sent from i9300 using Android Central.....

no i have not rooted my phone

Try updating your drivers in your comp... Also enable "USB Debugging" in Settings/Developers Options....
After doing these reconnect with Kies .....

Sent from i9300 using Android Central.....