Hi @Nasrink36,
Welcome to HP Forums, this is a great place to get support, find answers and tips.
Thank you for posting your query, I'll be more than glad to help you.
I understand that you get a red screen in the background of your Pavilion dv6 and it works fine when connected to an external monitor.
This could be a hardware issue with the unit as it is working fine with an external monitor.
Hence, you may need to contact HP phone support for further assistance at the link: www.hp.com/contacthp
You have a good day ahead.
Rainbow23 - HP Support.