Possibly Dead 5760

Hi I hope this is not going to be a super lengthy explanation of my current problem but here we go.

Last week my sager 5760 started acting up, I would turn on the laptop and I would get the three beeps about every 10 minutes, while at the same time the caps-lock-num lock lights would flash. When I would go into windows the three beeps come on and off until finally the computer just shut itself off.

At first I thought it was a virus because when i was logged on into windows the system seem to want to lock me out of it by changing the administrative password. I took out the hardrive and scanned it using another computer, and that would fix my problem.

Installed the hardrive once again and now the laptop would just go into a loop and would never log onto windows. I was afraid my hardrive had failed (like it had once before) so I popped in another hardrive that i had with windows installed and once again the loop began. So i determined it was not my hardrive

I then removed the memory modules tried to restart with one and then the other and nothing, until last night where the whole thing just went dead, it won't go into bios, the screen won't turn on, only the clock and the fans spin.

I am not sure what to assume, but I think it would be safe to say that my motherboard is dead? and if so how much does it cost to replace a motherboard?

I wanted to try to reload the bios but i can't seem to locate a copy of it if somebody could put me to one i would appreciate it.

I am going to try to remove everything but the essentials, wifi etc etc, too see if that helps but i do not have high hopes.

Thanks for any responses.