I have a problem with a Toshiba laptop L300D-10B which does not boot up. When i press the power button, the laptop turns on (power light is on, cd-rom works, fan spins) but HDD light is off and the screen is black-completely off.
- Power adapter tested with multimeter and looks ok.
- Power adapter changed with another one.
- Power is coming ok with no loss up to the motherboard pins. Tested with a multimeter.
- HDD connected to desktop and works ok.
- HDD changed with another one from a different laptop which works fine.
- Removed battery and power cord out of the laptop and then pressed the power button for over 30 sec.
- RAM removed and reseated one by one.
- RAM changed with another one from a different laptop which works fine.
- Disassembled the laptop unplugging everything.
- CPU unplugged and replugged.
- New thermal paste was applied on CPU and GPU.
- Fan and heatsink were cleaned from dust.
- CMOS battery tested with a multimeter and looks ok. (3.3 V)
- CMOS battery removed for a few minutes and resoldered.
- CPU changed with another one the same from a working laptop.
- A new monitor connected on the vga port. (Still black)
I don't know what else to do. I'm afraid that the fault is on the motherboard or the GPU. If you have any advise to give me, i would really appreciate it.
Thank you in advance.