The PIT file is the partition information table. It tells your phone where different packages go on the phone, as well as how big partitions are on the phone. Without this information, Odin cannot properly re-partition your device
QCN = Qualcomm Calibration Network
Q: Which phones support QCN file for writing/reading? A: All qualcomm based phones!!!!
Q: Why this file need? A: If phone EFS erased, wiped - phone calibration erased - and phone not see network/not see 3g/2g/LTE network.
Q: QCN file same for all phones of same models? A: NO. Exist lot of hardware revision of pcb and lot of different firmware for same phone, better to have collection of few QCN for same phone model, few times tested and after using same QCN 1st phone can work good and second phone can not work property.
Q: Can QCN fix UNKNOWN BASEBAND phone? A: NO, But if you write QCN from wrong model, you can got UNKNOWN BASEBAND! WHY?!! Becouse: You can write QCN only if phone modem work. UNKNOWN baseband - this mean modem not work!!
Q: Where i can get QCN? A: Best way - read QCN from fresh - non branded phones!!
Q: Will QCN file effect imei? A: NO, if you using z3x for write QCN, z3x not touch NV with imei!!!
Q: CERTI(FAIL) can be fixed by writing QCN?!! A: NO - CERT (signature for imei) not have any relation to MODEM CALIBRATION.