Q: My i5s with ios 9.3.1 is bluescreen of death when using safari, why?

Hello JOEYnkp, 

Thanks for using the Apple Support Communities!

From your question, it sounds like you are seeing a blue screen on your iPhone only when using the Safari app. If this is correct, there are a couple of different troubleshooting steps I would recommend. 

First, clear Safari’s history and website data using the instructions from the following article. 

Clear information from your device

To clear your history and cookies from Safari in iOS 8 or later, tap Settings > Safari > Clear History and Website Data. In iOS 7 or earlier, tap Clear History and tap Clear Cookies and Data.

To clear other stored information from Safari, tap Settings > Safari > Advanced > Website Data > Remove All Website Data.

Clearing your history, cookies, and browsing data from Safari won't change your AutoFill information. 

To visit sites without leaving a history, learn how to turn private browsing on or off.

Safari web settings on your iPhone, iPad, and iPod touch - Apple Support

Once that step has been completed, close the Safari application completely using the instructions from the next article. 

Force an app to close in iOS - Apple Support

After Safari has been closed, restart your iPhone. 

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

Open Safari and test after you iPhone has finished restarting. 

If I have misunderstood the situation, please give us further details about this situation so we can continue to provide assistance. 

Cheers!