if the phones only a month old then return it for a warranty repair,if it was second hand then you may have got yourself a stolen phone,many people lose or have a phone stolen and then report lost/stolen after a while when they are sure it is not going to be found,if this is the case then the imei number is logged on a database and it will show as no service or will just access the sim but never get a signal.if you are sure the phone is not stolen and is second hand then the best bet is to buy a new one mate,from experience with samsung mobiles then its not worth the hassle of taking it to bits as they are a slide phone and between the two halfs is a ribbon cable and it is so easy to damage and really expensive to replace if you do damage it.considering you can buy those samsungs now for less than £50 and the ribbon cables are £20 plus then as with most mobiles nowadays they are virtually a disposable item.