i have a massive development guys. my 2017, 13 inch, 4 tb3 ports laptop is back on business. i detached the webcam and now all is working fine. no more critical update prompt, nothing. of course i sacrificed the webcam but it's better than nothing. i don't use the webcam frequently anyways. i can live without it. when laptop disassembled the screen connector is facing north (speakers are south, towards you). webcam cable is on the right side of the screen connector, under the removable 3cm wide metal shield. there is a same connector on the left side of the screen. don't detach it otherwise screen is black. i think it might be screen backlight. now the laptop went to sleep but it seemed like it slept really deep. i woke the laptop by pressing a button and laptop didn't wake up instantly but with a startup chime, like you put it to sleep for long or restarted the laptop. but it resumed from it slept. now i tried it again but this time it woke up instantly. i am really happy now and i hope someone can benefit out of it. edit: out of curiosity i plugged the webcam back. boot up speed significantly reduced. nearly 5minutes. greeted with critical update message. forced the laptop to shutdown by power button. i plugged off the webcam cable and boot up speed was again same slow, around 3mins this time. i started worry if i caused the magical fix to not effecting anymore but it was all good again after turning on. it took longer to boot because i shut down the pc by power button and os x wanted to do a system check if everything was fine. turned it back on from shut down by power button and it turned on really fast. guess what touch id, sound, touchbar, all working. so it looks like they all have seperate controllers. i don't remember if there was a backlight on the keyboard but it doesn't work. i don't care about it. now my guesses are these -webcam cable cracked and don't have all its pins sending data to motherboard and causing lag and system instability therefore touch bar doesn't work. -a controller chip or sort is failed on the motherboard therefore a new screen replacement may not sort this issue out. this is something i will try in the future when i can invest some money on a replacement screen. so the infamous embeddedOS wasn't the problem on my case. i spent so much time on it. please let me know if it helped you too.