Boot problems, strange diagnostic leds.

My 2015 EMC2833 gave up on me and I don’t have a clue what it could be.

Are there any schematics available for this model? MB nr. 820-00431-A I have googled for a long time with no success.

I have removed the LCD to access the diagnostic leds.

When I connect power, both LED 1 and 2 lights up within 3 secs without me pressing the power button. if I push the power button the leds turn off and comes right back on again 2 seconds later.

But if I hold the power-button while inserting the power cable only led 1 lights up.

If I then release and push the power-button again led 2 lights up but no chime or fan-spin.

If I then hold the power for 6 seconds led 2 goes off and 1 stays on.

Why is there a difference if I hold power-button or not when inserting powercord?