Logo flashes, one line flickers, white screen flashes, cycle repeats

This iPhone 4Gs went dead while taking photos outside in cold weather. Apple store said the likely problem has to do with the display and/or digitizer and suggested replacing the phone. Screen powers up with Apple logo. The Apple logo keeps flashing. Yellow, red, blue and white horizontal lines flicker underneath or above the logo the entire width of the screen - one line at a time, one after another. The entire screen also flashes white. All this repeats in a loop when the phone is connected to a power supply. When not connected to the computer - the power button turns on the Apple logo, logo flashes once with one yellow/blue/white/red line underneath or abover and goes off/black again.