The 4 lights is due to it being an av detection problem. Meaning either the AV Cable is not plugged in or the AV sensor on the main board is out. This guide does not instruct on how to replace this board part.
Here is a quick help guide: 1 flashing red light: hardware failure 2 flashing red light: overheating; install a cooling center or cool kit 3 flashing red light: General Hardware failure; RROD the xclamps need replacing 4 flashing red light: AV Cable Error; HDMI Components excluded.