4s screen flashes after screen replacement

Hi,

I just replaced the screen on my 4s and am having problems

1- press power/lock button
2- screen turns on about 2 seconds later, sort of flashing white and there is a white spot in the upper left corner
3- screen turns off after about 5 seconds of this

phone is not booting at all, computer doesn't recognize it, battery fully charged etc.

Has anyone had this problem?

thanks in advance