| Error | Cause | Fix | |-------|-------|-----| | 0x8400F121: ADL error | Wrong USB driver / Phoenix version | Reinstall Nokia Connectivity Cable driver. Use Phoenix 2012.04 | | 0x8400F107: Timeout | Battery low or bad USB port | Use USB 2.0 port, charge battery externally | | Flashing failed at 12% | Corrupted SysFS block | Re-download firmware (try a different source) | | Device not detected | Phone not in Dead USB mode | Short testpoint (TP124) to force FBUS – but rarely needed. Try another cable. |

Flashing the full firmware (especially the PPM) can reset security codes to default (12345) and remove network locks if a proper patch is applied.