Dell Studio 1558 will not boot

Hello!

I have a Dell Studio 1558 that was working perfectly last night. This morning, however, it will not boot. I have tried booting with both the battery and AC adapter, just the battery, and just the AC adapter. I took the battery and adapter out and held down the power button for 45 seconds. I have also tried a (different) known good AC adapter (by itself and with the battery). I've also tried an outlet in a different room.

The weird thing is that every time I plug the laptop in, the LED turns on for about a second, then turns right off. I have tried hitting the power button for that split second that the LED is lit to see if it would make that initial boot sound (even if it doesn't fully boot up), but it doesn't. The battery has 5 LED indicators, but none are lit. I can't find a button on the battery to diagnose the battery life (some DELL forums were saying to hit a button on the battery).

Also, hitting Fn while attempting to boot does nothing - I saw that some DELL laptops had a built-in diagnostic. Not sure if that applies to mine or not.

I wouldn't mind taking my hdd out and booting without it (or testing the hdd itself), but laptops are kind of a pain to take apart and I'm thinking that it's not the drive. I'm hoping there are other things I can try first..

Please advise with further troubleshooting steps or any suggestions.

Thank you!