So I have this really old model and I haven't used it for 5 years. When I turn the laptop on, the fan starts really loud and then goes quiet. The power button lights up and so does the other lights.
1. I've tried connecting the laptop to an external display which just caused the external display to say "check video cable". Video cable is fine since I use it for another computer.
Tried taking out the battery and pressing the power button for more than 30 minutes but screen still doesn't switch on.
Tried checking if both the RAMs are working by testing if each of them work separately and cleaning them, screen still doesn't switch on.
One thing you can try to narrow things down is to start up in the BIOS. I don't know the key for that for your machine so you will need to find this. If you can see the BIOS information, that's a reasonable check that the CPU and graphics are working. You can then see if the memory size makes sense and if it finds a HD.
Note that with UEFI (which your machine likely has instead of BIOS) it has gotten harder to get to the BIOS (actually called the UEFI firmware). Depending on UEFI security settings it may be very difficult. Good luck.