What voltage does the equipment use? What is the voltage across each of the open switches?
Hi Aruen (or is it Auren ?).You can't simply connect an Arduino pin to some external unit and hope it will work, without knowing what signals are normally there.The buttons have a lot of solder pads, each button visible in your 2nd picture has at least 1 solder pad to each end.You could use those to solder the outputs of some relays to.These relays can be very small ones as there will not be large currents running through the contacts.So now you have to find out how to connect relays to an Arduino (because you shouldn't connect them just like that), it has been discussed a lot over here.You could also find out more details about the normal signals in this device of yours, maybe something simpler can be used.
Don't give up that easily.If there's a pic inside, it is likely that that is where these buttons go.They for sure aren't connected directly to the 230 vac.Relays are available in many tastes.You need to drive a relay, and by that i mean you cannot connect it directly to an Arduino pin.A relay is a switch that is controlled by electronics instead of by someone or something pressing it.The good part about that, is that the controlling part is not electrically connected to the switching part.That way it is safe to control different circuits with very little chance of damaging either one.If you can emulate a button press by shorting two contacts with a piece of wire, then you must also be able to do that by using relays.And soldering is a matter of practicing, i don't think it will be too hard to solder small wires to those pads visible on the pictures.If you want to do this without relays, you really need to find out how these buttons work, and what voltage is on them.