Just want to verify, the problem is it's showing green, white and blue on your external monitor but not in your laptop right?
- If it's happening only on your external monitor (TV), try changing the cable that connects the TV and the laptop.
- If the same problem will persist, do also try a different monitor or TV.
- Next to try is to do a clean install of the graphics card driver.
- Go to Device Manager and uninstall the graphics card driver.
- Open Programs and Features then uninstall anything related to the graphics card.
- Once done, download and install the latest driver.
- Reboot the laptop once the driver has been installed.
- Do test it again and see if the same problem will persist or not.
- If the same problem will persist the problem lies in the GPU itself.