If you are looking for the official stock firmware for the Vivo NEX 2 Dual display, you can download it here. The firmware is useful for fixing software related problems like.
- Boot loop
- Un-rooting your phone
- Update firmware
- Restore to factory defaults
- Fix malware/monkey virus etc
Download Vivo NEX 2 Dual display PD1821F Stock Firmware
Download the stock Android 9 Pie firmware for your Vivo below. Flashing is via QFIL.