SPI Flash should be erased in OOWOW.

Please refer to: tips to boot OOWOW.

After booting into the OOWOW system, select the following options:

Advanced → SPI Flash options –> Erase SPI Flash Fast - boot areas only or Erase SPI Flash FULL - slow

• Erase SPI Flash Fast: Erases only the boot areas in SPI Flash; this takes only a few seconds.
• Erase SPI Flash FULL: Erases the entire SPI Flash; this may take a few minutes.