RAM Problem with a Laptop?

Hey Guys! would really appreciate some help here! i have a Fujitsu Siemens AMILO Laptop here and i tried to remove the RAM and upgrade it from 500MB to 1GB and the Laptop wouldnt turn on without the power cable so i removed the newly added RAM and reverted back to the old 256MB and now the same problem is Occuring!!! the Laptop will turn on and whirl and do its bit but it will show nothing on the monitor at all, it begins by flashing the plug in button and then it evens out but the Laptop itself appears to not be responding...however the monitor is showing nothing and the Disk tray is whirring a bit too!! I NEED HELP!! ANYONE GOT ANY IDEAS??