iPhone 14 running iOS 18.6 shuts down after a couple of minutes

wemanke wrote:

I just had 18.6 software installed last night.

Plug it into power—

Put your iPhone in diagnostics mode - identify potential hardware and software issues

How to put your iPhone in diagnostics mode - Apple Support

The current stable release of iOS including bug fixes, security updates is your iOS 18.6

Update your iPhone or iPad - Apple Support

Restore from backup, restore as new device.

Restore your iPhone, iPad, or iPod to factory settings using a computer - Apple Support

If you can't update or restore your iPhone - Recovery mode

If you can't update or restore your iPhone or iPod touch - Apple Support

you should go to the nearest apple care service center and downgrade your ios and the problem will be solved.

When was the last time that you replaced the battery?

Was there a message that appeared on the screen before the phone shut down? If you recall, what was the message about ?

Tap Settings > Battery > Battery Health & Charging and report on the current settings for Maximum Capacity

Check in Settings to see what your Battery Health is, and what the Maximum Capacity is reporting.

nitinbaisoya wrote:

you should go to the nearest apple care service center and downgrade your ios and the problem will be solved.

You cannot downgrade iOS. Apple does not provide a path to do this, and taking it to an Apple care service center will not accomplish that either, as they cannot and will not downgrade iOS.