If you have a MediaTek-based KaiOS phone and can't enter Fastboot with a combo:
- Press "Enter Fastboot (MTK)"
- Insert the cable
- Quickly connect to MTK preloader port once it appears in the browser USB menu
Once you're in Fastboot mode, do the following:
- Press "Jailbreak"
- Connect to "Android" port once it appears in the browser USB menu
After reboot, the Developer menu should appear in the Settings - Device section.
If the flashing doesn't succeed:
- Reconnect in Fastboot mode
- Press "Attempt OEM unlock"
- Repeat the whole procedure