Chosen Solution
I tried the usual PRAM reset, no response, I connected to external screen, no signal, I tried T mode , no icons on neither internal or external screen. I removed the native LCD, to check the LED lights, I have 1 and 2 but no 3 nor 4. That would mean logic board is toast, right?
If you disconnected the display LED’s 3 & 4 will also won’t light. So you need to make sure the display is wired up to be sure. You likely have a burn’t GPU board.
