Dell Latitude d531 won’t start up

Beginning on last Friday morning, my Dell Latitude d531 (bought in 2007 so I no longer have warranty coverage) has not been starting up. I forgot to shut it down before I fell asleep and although I wasn't having any issues with it recently, I figured it may have just overheated. I cleaned the fan out and there was nothing blocking it.

The issue is that when I press the button to start the laptop, I hear the fan start up briefly (as if the computer were starting up like it normally would) but the screen remains black the entire time. In the row of Device Status Lights, only the power button light turns on & stays solid green. Nothing happens to the others (battery, WiFi, etc).

I tried a few things I read online as tips but had no luck with them:

-  Tried turning on laptop with battery taken out & power cord plugged in. It didn't make any difference.

-  I tried removing any static buildup by unplugging the power cord & removing the battery, holding the button to start the computer for 10 seconds, and then reinserting the battery & power cord, but nothing happened.

-  I also held Fn as I pressed the power button to start my laptop. In the three Keyboard Status lights (Number lock, caps lock, and scroll lock), all 3 light up solid & then the Number lock & caps lock lights start blinking while the scroll lock light stays solid.

I’m actually planning on buying a new laptop soon anyways so if the issue is that the motherboard needs to be replaced, I’ll probably just forget it, but if anybody thinks there’s something else I could try without hardware replacement, please let me know. I appreciate the help!