Q: unresponsive iphone 6

"Why" questions are nearly impossible to answer on these forums.

If your question is "My iPhone 6 is unresponsive.  How can I get it to work?", then that might be possible.

Place your iPhone into recovery mode as described here.  You may have to try to enter recovery mode more than once to succeed.  Be certain you have the current version of iTunes on your computer.

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