A: You erased the NVRAM. You need to restore your IMEI using a tool like Maui Meta or take it to a repair shop.
OPPO A5 (2020) Flash File: Stock Firmware Guide (CPH1931 & CPH1933) oppo a5 2020 flash file
/oppo-a5-2020-flash-file-firmware Introduction A: You erased the NVRAM