When the motherboard boots up, it makes 'beep's to tell you information about the health/condition of various motherboard components. Usually a short single beep indicates "all is goog" but you hear anything else, like multiple short beeps, the manual generally interprets the beep pattern into plain language message as to what part failed. The failure of ANY part that is physically on the mortherboard, not plugged into a socket, usually mean
the motherboard has failed. It's possible, but not easy to replace mother board components. They are small, the soldering joints are small and if you don't know how to solder/unsolder on printed circuit boards generally you'll do more damage than was previously the case before you tried. Just identifying the specific part can be challenging, again, especially if you've not done this level of precision work.

The solution: get a new motherboard, and while you are at it, get a new CPU and memory sticks if you want to be on the safe side. Not all CPU's fit every motherboard, and memory sticks come in several configurations. Anytime I replaced a bad board, I got the whole package and asked the technician to assemble them and let mee see it boot up at least the point where it requests a proper boot media, such as a harddrive or bootable DVD/CD.