On power up- one beep, fan runs then nothing

iMac was in storage for 2 years. First try to boot up = 3 beeps,fan on then nothing. Cleaned and reset memory stick, checked 1/2AA 6.5v batt.(reads 7.0v). Now power up = 1 beep, fan on, then nothing. Don't know how to open CD drawer if the original boot disc or a repair disc is needed.