My laptop went down and does not start again

Hello,
a few days ago my laptop suddenly shut down. I tired to restart it but it did not boot. After waiting several minutes, I tried again to restart it and it worked but after a couple of minutes it went down again. Since that it has not started again. When I turn it on I get no video signal and no beeps. The only led on is the power one and the fan works, too. I have tried to remove the RAM to check if it is faulty but the same response, neither video signal nor beeps at all. I think the motherboard is dead but I am not sure how to check this.
If you have an idea about which the problem could be please give me a post.
Thanks in advance.