Hi AnnaCTam,
Let's try this. Turn the system off, unplug it, and hold the power button for a few seconds to dissipate capacitance. Remove the RAM modules and disconnect the hard drive. Plug it back in and try starting it up. You should get two beeps, indicating that no RAM modules are detected. If you get anything else, let me know.
If you get the two beeps, plug the hard drive back in and one memory module and try again.
