My computer has a black screen.

Hello,
My computer was turned on for 6-7 hrs. and after that it shut down automatically so i decided to turn it on again but it started hanging during the POST (memory test), after a number of restarting it ended up with a black screen. I already tried to use an eraser to clean the gold plate in the memory and reseat it, but nothing happens. I have also tried to start my computer without any RAM and i received no beeps. What do you think sir is faulty?
Thanks in advance!!