im on 20k firmware. i rooted with ioroot25 then autorec to downgrade bootloader and flash twrp 188.8.131.52. i later ran towelroot for the hell of it. i can never get official twrp to flash because they dont use loki_tool for some reason even on the latest builds. i was able to flash philz_touch fine since loki is done properly. philz_touch is also nice cause it allows u access to many more partitions then twrp. i did make the mistake of letting the phone take the ota update a couple times and bootlooping until i fixed the issue by zeroing the nessacery partitions and removing the system files used for taking an ota. i thought about flashing back to stock and otaing up to 20y to get the latest firmwares on the other partitions and the "knock code" update. then root with stumproot and bootloader/recovery with autorec. since i have been tired and stressed lately i did not flash back to stock. i since have flashed latest dorimanix kernel which has bump support and f2fs. i then discovered that blastagator created bumped builds of latest twrp. since that gives u latest bumped kernel and latest bumped custom recovery things felt a little better with this phone. i found out blastagator made a bumped kk bootloader which i flashed successfully. i also downloaded but havent flashed blastagator's bumped jb/kk hybrid modem.
at this point i feel like my phone might be prepped enough to flash custom roms. i am concerned about not having the "knock code" firmware update since dorimanix states you should update your firmware to it for latest kernel builds. i can verify that i can only make the phone sleep by double tapping the screen but not waking it. i can only assume that flashing latest firmwares might be required for future roms and kernels like on other devices.
since we now have a way to flash kk bootloader and jb/kk hybrid modem i wonder if there is a way to get "knock code" update and other important firmware updates without having to flash back to stock 20c then otaing up to 20y?
if i decide to flash a custom rom without "knock code" firmware update would i regain the ability to double tap the phone to sleep and wake it again? or is it lost to me until i flash back to stock and ota up?
I have no idea what state your phone is in. You really went medieval on it.
I would say at this point try it. And if something fails go back to stock and then root through autorec.