Okay according to documentation, repeated long beeps when the computer starts means the memory problem. I confirm the memory works on another computer; and I tried a memory from a working computer--same thing, repeated long beeps. Tried the other slot, same thing. Not putting memory at all, same thing.
It's built-in video card, so no way it's not seated properly. I dusted everything. Reset the bios (by taking out the battery for 30 minutes).
Before it happened, I was swapping the CD drive with another. Worked fine. Swapped them back. Did not test it, but I went to PC store to get a new CD Drive. Then I plugged in the new CD drive and I got the repeated long beeps. Put back the old CD drive, same thing.
Any other suggestion to troubleshoot it? THanks
Edit: 1 beep is about 7 seconds long, then 4 seconds delay, and looping.
Edit again: I bent a pair of pin on the mobo for CD drive, and likely it happened today. I straightened it already, but could the mobo have been damaged when I bent the pin, and cause that beeps?