If your F670L is semi-bricked (in a boot loop), you can force a firmware link via TFTP.
To conclude, there is . Providing one would be irresponsible, as it could destroy your hardware. zte zxhn f670l epon firmware link
The WiFi chipsets are different (Qualcomm vs Realtek). V6.0 uses Qualcomm; V7.0 uses Realtek. They are binary incompatible. If your F670L is semi-bricked (in a boot