Some users report Invalid IMEI or Baseband issues after a full reset or flash. This often requires a specialized "Repair" or "Restore Factory" step within the UMT tool or using a specific QCN file.
module is the standard choice for this Qualcomm-based device. Vivo 1801 Flash File Umt
If the device is dead after flashing, re-flash with a different version of the firmware 1.2.1 . Some users report Invalid IMEI or Baseband issues
No, but it is the most effective for auth-bypass and dead boot. Vivo 1801 Flash File Umt
Yes. Flashing any unofficial software voids the manufacturer warranty.