Laptop powers up, fan is going full blast, but nothing else happens?

I got a used Vostro 5471 from a friend. It worked fine at first, then, after six months

not using it,  all that happens when I try to power it up, is the fan starts up in hyper

mode, and won't stop. Nothing else happens. Black screen. The keyboard lights up

though. I tried forcing it to enter bios with F12, and every other key command I

could think of, but no response. LED flash code by the AC power connector was

giving a "bios not found" code. I decided to replace the CMOS bettery on the

motherboard with a brand new one, but after installing it, no difference,

just the fan going on steroids. nothing else happens?