Easy Repair "OPPO Wipe Failed Syndrome" without change the EMMC using UFIBOX.
This is common problem on most OPPO Mediatek Devices with SKHinyx eMCP inside.
Like Oppo R815, R821, R827, R831, R831K, R1001, R2001, etc.
We use Direct ISP to Repartition The EMMC,
▫ Solder only 4 wire : CMD, CLK, DAT0 & GND, use Usb Data Cable for VCC & VCCQ
▫ Factory reset emmc, do repartitioning, and write preloader
▫ Flash devices with stock rom using any mediatek flasher you have
▫ And You're DONE.
Latest UFI Android Toolbox already support Flashing and Repair Imei of Mediatek Devices
https://www.youtube.com/watch?v=mVAj4QPkIAs