Dear brother.
Sab se pehli baat tou ye k Odin ap tab use kr skty hain jab ap ka device original samsung manufactured ho, korean na ho. Dusri baat kisi b samsung mobile ki jo ap AP wali file keh rhy hain jis se software flash hota hy usko stock rim lehty hain. Stock rom download krny k liye ap google me ye keyword dy skty hain....
Model number stock rom. Bilfarz ap s3 i9300 ka firmware download krna chahty ho tou ap ko i9300 stock firmware likhna hoga. Diye gye links me se download kr len