extreme battery drain after updating ios 9

Have you tried any troubleshooting?

Restart: Press On/Off button until the Slide to Power Off slider appears, select Slide to Power Off and, after It shuts down, press the On/Off button until the Apple logo appears.

Reset: Press the Home and On/Off buttons at the same time and hold them until the Apple logo appears (about 10-15 seconds).

Restore: Connect your iPhone to iTunes on your computer, backup, and then select Restore to Factory

Did you actually Restore as New? Don't restore a backup afterwards or you will simply restore whatever is causing the drain.

Family Sharing may be draining your iPhone’s battery

Eight Battery Saving settings for your iPhone and iPad | MacIssues

The Ultimate Guide to Solving iOS Battery Drain — Scotty Loveless