Help with my laptop weird no bios, no backlit issue

[bien029]

Hi! First of all I did search a lot about this issue and I can't seems to find a solution or similar to my problem, here's the story, the laptop is old (I know, but i use this only for school paper works, xubuntu OS) Toshiba Satellite Pro L300D at first I thought it was dead because of the brick BIOS, so to check I've done some troubleshooting:

Ram check
Hdd check
Boot with F key pressed
Even desoldered the cmos battery terminal and solder it back after an hour (Iknow how to solder don't worry)
Boot with external display
No battery boot
5 minutes press of the power button to drain the remaining electricity
And a combinations of above

BUT after not using it almost a month it magically boots up perfectly, then I started using it again for a month, then my professor told us to install a windows OS because he wants us to use the program that is only available to windows so I dual-boot my latop, installed the software, then I decided to installed Bitdefender as my AV but after it restart it didn't boot to windows desktop (just a black screen with a mouse pointer) so I decided to go into safe mode and disable the AV but after I force shutdown the laptop, the problem started to exist, it's not booting up again and now I regret installing that AV.

Is anyone here know exactly what am I facing?

 

[hang-the-9]

Lots of info but you don't really say what the issue is.

You turn on that laptop and what exactly happens? No display at all? That points to a bad screen. If it does not work with an external monitor either, that points to a bad video chip or motherboard.

 

[bien029]

Lots of info but you don't really say what the issue is.

You turn on that laptop and what exactly happens? No display at all? That points to a bad screen. If it does not work with an external monitor either, that points to a bad video chip or motherboard.

Ooopss sorry, when I turn on the laptop with just power adapter, no display, no lights on screen, the power led is on, the on/off led just turns on the rest is off (HDD led, MemCard led, etc) but when I tried to pressing the function (Fn) button the indicator lit up.

If it's a bad mobo, that means I have to give it up, but I am waiting for a month to test it again see if it'll work magically again. Anyway Thanks!