Dell Inspiron 3521 won't start -- power light and fan come on, but screen remains black

[KuroKage]

Dell Inspiron 3521 won't start -- power light and fan come on, but screen remains black

The laptop will no longer turn on, and I just get a black screen, but there is no problem with the power supply as the light comes on.  Further information:

• The power light comes on when the cable is plugged in
• The battery charging light comes on when the battery is in place
• The fan comes on after pressing the power button, but the screen remains blank and the laptop does not boot
• The HDD light turns on at the start but turns off like 2secs later
• I have tried removing battery & power and holding the power button down for 15-30secs but this doesn't help
• I have tried starting the laptop with memory and HDD removed, but I get the same symptoms
• Plugging into a external monitor via HDMI gives no signal

i tried removing the cmos battery and putting it back after 1 hour but nothing changed. 

pls help

[KuroKage]

The laptop will no longer turn on, and I just get a black screen, but there is no problem with the power supply as the light comes on.  Further information:

• The power light comes on when the cable is plugged in
• The battery charging light comes on when the battery is in place
• The fan comes on after pressing the power button, but the screen remains blank and the laptop does not boot
• The HDD light turns on at the start but turns off like 2secs later
• I have tried removing battery & power and holding the power button down for 15-30secs but this doesn't help
• I have tried starting the laptop with memory and HDD removed, but I get the same symptoms
• Plugging into a external monitor via HDMI gives no signal

i tried removing the cmos battery and putting it back after 1 hour but nothing changed. 

pls help

[ejn63]

If you didn't hear a two-beep sequence when you tried booting without RAM, the mainboard is toast.

[KuroKage]

when i boot up withou ram i hear 4 beep sequence

[ejn63]

The last thing you can try is powering up on AC only - no battery.  If that gets the system running, the battery is bad.  If it doesn't, the mainboard is faulty.

[KuroKage]

no the battery is not the issue.
when i remove it and start up the pc i get the same issue.

[ejn63]

It's time to replace the system board (or replace the system;  this one may not be worth such a major repair, given its age and low-end nature.