Q: After ios 9 update, iphone 6 has no display.

Hello Shinbal,

After reviewing your post, it sounds like the display on the iPhone is black. I would recommend that you read this article, it may be able to help the issue.

Get help with the screen on your iPhone, iPad, or iPod touch - Apple Support

If you see a solid color screen (black, white, or blue)

1. Plug in your device to a power source. If you see the low-battery screen when you plug in, let your device charge for at least 10 minutes (20 minutes for iPad) before using it.
2. Force restart your device while it's plugged in.
3. If this doesn't work, restore your device.
4. If you still see the issue after you restore, contact Apple Support.

Thanks for using Apple Support Communities.
Have a nice day