Pink & Grey lines - iPhone 4 is dead

Just got it replaced (today).

They gave it to me with iOS 5.0 installed.

The only thing I did was trying to update it to 5.0.1 using iTunes.

I immediately got this "pink&grey lines" screen.

It doesn't turn off, no button works (even if pressed and held together).

It is not "seen" by system profile (USB - no iPhone attached).

I'm just waiting for the battery to die. The iPhone LED is always ON, so it shouldn't take long.

I set up a call with Apple and probably get another iPhone tomorrow but I wish to know what's going on.

Any guess?