Replying to this 2 months later with a solution. I've seen a YouTube video where they suggested to hold the power button down for ~30 seconds. Tried it and guess what, the system booted perfectly fine attached to an external display through the HDMI port. The only downside of this is, of course, the internal display not working. I suspect maybe the LCD cable got damaged, since I reconnected it in both places and it still doesn't want to detect it.
Hello! My Dell Vostro 2521 does not do any beeps or show anything on the display when started up, only the power on indicator and thr battery charghing indicator light up. But, if connected to an external display, the laptop displays this weird message for a second, then a blank screen, followed by 8 beeps from the laptop. What could the problem be? [IMAGE]  
Dell Vostro 2521 weird problem