TriggerFinger

So after putting everything back together you tried powering ON (using AC adapter I believe) but you did not get any sign of life except for the charging LED that gave off a flash for like half a second. No other LEDs lit up. No activity from the drives. No beeps..

Try removing the battery and run on AC only. If symptoms persist, strip the computer down to keyboard, motherboard and LCD. Make sure RAM is mounted on its sockets properly and securely.