Here is Check List when you will buy for new:

Before Open the Box

1. Check Box Condition?
2. Check if Seal is not broken?
3. Check if it has Local Authority Approval (DirJen Postel Approval for Indonesia)?
4. Check IMEI and Pin Label is geninue?
5. Ask whether the Keyboard is QWERTY or QWERTZ?
6. Check validity of IMEI here

After Open the Box

1. Check IMEI numbers near battery compartment, IMEI should same with the box
2. Check IMEI by type *#06#, IMEI should same with the box
3. Check Data and Voice Usage time by type BUYR at Options – Status (must 0)
4. Check Status Phone by type MEPD at Options – Advanced Option – SIM Card
5. TEST hardware