Sometimes during a power outage, the operating system gets garbled on the hard drive. This usually requires a reinstall of the operating system and then restoring from your back up (you do have back up don't you). However it seems that you further complicated things by taking out the SDRAM and probably zapped it with some static thus the blank screen at start up. You will have to replace the memory. Please use static safe procedures when handling memory cards as you may not feel the static that can destroy the chip. Afterwards reinstall your operating system.