Imac 20" mid 2007 A1224, clicks no beeps.

My Imac previously would give me 3 short beeps, 3 long beeps , 3 short beeps. I saw in a forum it could be the memory so I replaced it with Mac approved memory. No change. I tried all the clearing and resetting to PRAM and other procedure suggested, no change. Tried replacing Logic Board battery, no it clicks but no beeps. Is it the logic board? Suggestions?