Ans:Led or LCD is glowing means back lit is working fine but Screen Pcb Not getting supply which is 3Volts called VCC_lcd or say energy from Motherboard.
Possible reason: Cable may damaged, laptop motherboard not sending supply to Screen Pcb or screen pcb is faulty may be fuse open on screen pcb.
Solutions:
1. Open the Screen from its cover connect the cable to screen and motherboard after checking cable physically. Check the 3volts supply on screen first if its present then screen pcb is faulty need to replace Screen or you can repair the screen depends on your skills.
2. If LCD_VCC is not present then check the cable connectivity with mother board at connector JP24 pin No.38&40 if here supply is present then your cable may be faulty so replace the cable.
3. If LCDVDD red boxed in our pdf case is not present at CN24 Pin 38&40 or L21 then back trace to Q3 mosfet which is working as switch P type mosfet switching or not may faulty. if faulty replace it. if still no lcd_vcc/lcdvdd please follow the signal responsible to switching along with Q29 in our case its GMCH_LVDDEN in green box if not present then this signal being originated so find the possible reason and part responsible.
