The development community relies on a series of exploits, most notably the "Amonet" exploit (and its variations for the 10th Gen). This is a "dirty cow" type exploit that leverages vulnerabilities in the MediaTek kernel to gain temporary root access and disable the bootloader verification.

lacks the necessary developer tools to bypass the Secure Boot.

Go to Settings > Device Options > System Updates . If you are on Fire OS 7.3.2.1 or lower, proceed. If higher, you are currently locked out (though new exploits may appear in the future).