Welcome to HP Support Forums. 🙂 I came across your post and would like to help.
I understand that you have an HP Pavilion g6t 2000 laptop and the screen flashes when you open the laptop or when it resumes from sleep mode.You have to move the lid back and forth to make the display appear normal. I appreciate the steps you have performed and have certainly done a good job.
I did some research on this case and have concluded it is an internal hardware defect and suggest you to contact HP phone support to explore the hardware service options for your laptop.
Please feel free to let me know if you have any questions. Cheers! 🙂