iPhone 4s has Black screen and is in recovery mode

Hi,

I just tried to replace a screen on an iphone 4s but after the replacement the iphone won't boot.

So I connect the iphone on my computer and iTunes tells me the phone is in recovery mode but screen is still black and the motherboard gets hot.

I tried to restore the iPhone but the restore won't get to the end and i have no error.

I already repaired hundreds of phones so I'm not a noob.

If someone has an idea and thinks knowing what went wrong is welcome :)

Thank you for your help !