Dell d820 won't boot past initial Dell splash screen?

I typically leave my computer plugged in and it has been working great until now. Last night I just closed the lid which I have set to "Do nothing" and left for a few hours not realizing that the power adapter came unplugged. When I got home I just tried to boot it then plugged it back in, now it won't start up. It loads the entire grey bar at the beginning and all the lock lights turn on as well as the power and Bluetooth lights. Then it goes to a blinking cursor, then black screen and it starts all over again, I ran diagnostic and everything is fine apparently, I took out the battery and tried running just off power and no matter what the combination with battery/power, the boot is always the same. It occasionally stops on the blinking cursor and just does that the entire time. I don't have discs on hand, but if I for sure need them I could probably get them somehow? Let me know if you can help, and if you need more information. Thanks! Cheers!