Aspire 3680 - Flickering screen during bootup

I am repairing a laptop for a friend of a friend. They gave me the laptop with a dark screen (not even flickering). They were told by a computer store that it was the backlight giving them the problem. I went ahead and replaced the screen and found out that did not help. I then replaced the inverter and got it to at least somewhat work. Now, during bootup, the backlight will flicker on part of the screen, then the whole screen, then stop flickering after a while. By the time it gets to the windows logon screen, the flickering stops. It is like the bulb or inverter has to warm up. If the computer stays on, it will not flicker again. This problem will not occur if I just turn the laptop on then off. It seems like if I let it cool down, it will recur. I get this behavior on both screens, so that can be ruled out. Could it be a bad brand new inverter?