No need to make flash before unlock, just:
1. make full reset *2767*3855#
2. Click Read codes
3. Connect cable to phone (C3300K)
4. Connect battery
5. Hold down power button
If you put battery, then cable, and the push power, will not go in TAT mode.
Selected model: C3520
Selected com port: COM6
Selected speed port: 921600
Please, connect phone and press power button 3 seconds
Phone Detected
Use automatic parameters
Phone in TAT MODE
Phone IMEI: 35526105638155
Phone SW: C3520XXLI1
Phone CSC: C3520AMNLI1
Phone BT ADDR: C488-E5-8AD1A8
Phone SN: RV1D17ABX9
[FREZEE]:61404430
[NET LOCK]:47189060
[Subset LOCK]:00000000
[SP LOCK]:00000000
[CP LOCK]:00000000
[Sim LOCK]:00000000
[Activa LOCK]:00000000
[Phone LOCK]:00000000
Read info - ok
Elapsed time: 20 second, sw ver: 3.5.0040
Thanx Z3x team