Hello /wsr/, I have a broken old rear-projection TV lying in my room. These old TVs work by, as the name says, projecting an image through a set of LCD lenses and mirrors with the help of a bright lamp. My TV has a set of safety switches around the lamp plug, but one of these micro switches is physically broken so the TV refuses to turn on as the mainboard detects it as 'not in place'. the led indicator sequence matches that error. I looked up the service manual and came up with this
https://www.manualslib.com/manual/855317/Sony-Kdf-E42a10.html 