How to unlock Nokia 520 security code Without Flash

Remove Nokia Lumia 520 security code

1. press and hold the power key
2. phone vibrates (release the power key)
3. press and hold the V- key
4. exclamation mark is shown on he screen (release the V- key)
Step 2
Input the key combination:
1. V+
2. V-
3. Power
4. V-
Step 3
 The phone will reset and boot up automatically.

Step 4
  Try, step-1,2,3 not ok Then Try Full Flash With ATF Box