Hello, here is a UE50MU7000 with BN41-02568B (after an electricity jump):
- no stand by led light
- power supply has 9v outputs which go to mainboard
- without mainboard connected backlight works fine
- without backlight connected still no stand by led light
- dumped 24C512, 25Q40, 25Q80 (through CH341A programmer before finding this site), and flashed backup data from a UE40MU6102KXXH (which has same main board), this did not fix anything

After reading this thread, found out there is a specific way of flashing 25Q40, so I've placed all original backups...