the ios 8.4 update problems with my phone

Force your device to start. To do this, press Sleep/Wake and Home buttons and hold them for at least 10 seconds.

Take a look at this support article: If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on - Apple Support

Try to reset your device. This won't delete your data stored on the phone.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

Alternatively, you may go to Settings - General - Reset - Reset All Settings

https://support.apple.com/en-us/HT201559

If this does not help, restore your device to factory settings. Note that this will erase the data from your device.

Take a look this Apple Support article: Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support.

As a final step, try the recovery mode. Turn your device off, then plug it to your computer with the home button pressed. You will need to have iTunes installed on this computer. Keep the Home button pressed until you see the iTunes logo on the screen of your iPhone. After that on your computer you should see the iTunes window saying your iPhone needs to be restored to factory settings. Click on the restore button.

More info here: https://support.apple.com/en-us/HT201263

Hope this helps!

I am having the exact same problem! I've done what you said and it extends the period of time that I can use the phone before it restarts however it still continues to do it! I have precious content that I cannot loose. What now?

I have same problem. I restore my iPhone as new still same problem. Shut Dawn then restart then black screen. Is any one find the solutions?

Did you fix the problem? How?

Thanks

the 5s does nothing but search since updating to 8.4 several days ago, I have reset & restored numerous time to no avail, it gains LTE signal for a couple of minutes and then back to searching....... sure would be nice to roll back to 8.3 to see if that clears up the problem

The one thing I have learned is to NEVER, EVER, EVER update when Apple releases. EVER. The update to my iPad2 from 7 to 8 has rendered it almost useless. Yes, you read all kinds garbage people suggest to "make it better". None of that crap works or if it does, not for long. Total waste of your time. I have an iPhone6 thru work. I will NEVER update to 8.4. It works great right now. I am POSITIVE it will be all cocked up if I update it.

Thanks Apple for sucking.

My iphone 5s with ios 8.4 gets heated and shuts down. Saw a blue screen once, much like windows blue screen error. 😐

Having a similar problem, my iPhone 5 would suddenly restart the last few days, I was going to restore it to factory settings but before I did that it just turned off by itself and I haven't been able to turn it on again, it turns on, goes to white screen with apple logo for a bit but it doesn't go any further than that, I've tried recovery mode and restoring it from iTunes but it restarts after a while so iTunes can't complete the restore....