iphone 7 losing battery power quickly after 10.3.3 update.

Hi

Depending on the nature of the issue, your iPhone may require battery service.

Before contacting Apple, try the following steps:

Restart your iPhone (normally):

• Restart your iPhone, iPad, or iPod touch - Apple Support

Check which apps are responsible for battery usage:

• Go to: Settings > Battery > under Battery Usage, select the Last 24 Hours tab.
• Address any issues with potentially problematic apps (such as by removing and reinstalling them).

Follow Apple's tips for maximising battery life, as detailed here:

• https://www.apple.com/batteries/maximizing-performance/
• About the battery usage on your iPhone, iPad, and iPod touch - Apple Support

When charging your iPhone, follow the instructions in the following support article, including:

• Checking the charging port for any debris.
• Using only a genuine Apple cable or an Apple-certified (MFi) cable.
• Apple recommends using the supplied USB Power Adapter.
• If your iPhone, iPad, or iPod touch won't charge - Apple Support

Check whether the issue persists after restoring your iPhone to factory settings:

• Back up your iPhone (you may wish to encrypt the backup, if using iTunes):
  • How to back up your iPhone, iPad, and iPod touch - Apple Support
• Restore it to factory settings, with a fresh copy of iOS:
  • Use iTunes on your Mac or PC to restore your iPhone, iPad, or iPod to factory settings - Apple Support
• Check whether the issue recurs before or after restoring from backup:
  • Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

If the issue persists, I suggest that you contact Apple Support (remote diagnostics and mail-in service may be available), make a Genius Bar reservation or visit an Apple Authorised Service Provider for assistance, including - if recommended - to arrange for your iPhone to be checked and serviced:

• US: iPhone Service Answer Center - Apple Support
• Elsewhere: Apple - Support