Proceed at your own risk!
1. Download latest odin tool.
2. Download twrp for china variant:
https://twrp.me/samsung/c9ltechn.html.
3. Flash twrp and check if stock rom is not corrupted, if not, nandroid backup.
4. Now wipe everything in the phone.
5. Download rom (nougat), SM-9000 firmware is compatible with the SM-9008 hardware (check my image attached) but download the "hong kong" region firmware. Basically your changing your Asia phone to an international phone.
https://www.sammobile.com/firmwares/galaxy-c9-pro/SM-C9000/TGY/download/C9000ZHU1BQL3/200864/
(If you want different sites... Google "samsung c9 pro hong kong nougat stock firmware" and download the sm-c9000 rom and flash it)
NOW AFTER THIS YOUR PHONES IN INTERNATIONAL STATE. DO NOT FLASH CUSTOM RECOVERY AGAIN, IT WILL SOFTBRICK!!!!
ENJOY USING YOUR NEW ROM. feel free to clear more doubts.