This may be simple but can be easily overlooked.
- Are you sure you are reading the two LED lights correctly? For example, the top one lit and bottom one unlit indicates that the memory is off. But are you sure the top one is actually the top one? Or that it is memory that is the problem? IIRC, for Biostar, if one LED is not lit, it means (as you said, a memory error) but if the LED's are reversed (top unlit, bottom lit), it should be a VGA error, which would explain why your monitor is not booting up. And if it is a VGA error, is your video card plugged in correctly?
May sound simple, but it is a problem I had to resolve from a friend whose problem is identical to yours. Hope this helps, and if not, at least you eliminated one possibility!