Stock kernel cannot boot into recovery as recovery is in a different partition and the bootloader starts only the /boot partition on startup. Therefore, we have a patch in the custom kernels to chain-load the recovery which resides in the /fotakernel partition after flashing with a button combination.I can for the life of me not get any version of TWRP to work.
- Coming from official latest firmware
- Unlocking bootloader
- Flashing TWRP through fastboot -- holding volume down and power -- boots into android
- Booting TWRP though fastboot -- screen remains black, blue light stays on
This is why rootkernel (a locally patched stock kernel) has the recovery bundled inside the kernel image. Custom kernels like GreenKernel or Zach's kernel have the chain-loading patch which allows them to boot recoveries flashed via fastboot like this one.