Ios10 with iphone6s - screen issue during hard restart

Hi,

i'm using a iPhone 6s and iPhone SE, After i upgraded my phone to ios 10 i started having screen problems. Normally when i hard reset my phone, the screen turns into dark black as it shuts down. But after ios 10.0.2 when i hard reset my phone the screen sometimes turns into blue, some times it shows gray, sometimes yellow (each time weird colors).I'm having this problem for past few weeks. I contacted apple customer support on this and they advised me to restore the phone using iTunes, and i did but no success , then i was advised by apple support team that, to visit the genius bar team to inspect the phone to make sure the phone has any hardware issue.

I have restored my phone many times in 2 days,but nothing has changed.

But when i do the normal restart by pressing power button then i don't see the weird colors.

So i wanted to know whether this issue has been faced by any body else, and whether this is really software bug issue or really hardware issue, according to me i suspect it is software issue only.

I will appreciate if anyone can find a solution

Thanks