[sergedouai]

Hello I'm in Côte d'Ivoire I have an infinix x557 that I rooted from TWRP and after that I downloaded the nougat version. after the download, the update started and the phone remained in twrp mode. good the phone remained in TWRP mode, I installed the boot.img image and I have since turned off the phone does not start anymore it remains on the logo infinix

[xerxes]

Hello I'm in Côte d'Ivoire I have an infinix x557 that I rooted from TWRP and after that I downloaded the nougat version. after the download, the update started and the phone remained in twrp mode. good the phone remained in TWRP mode, I installed the boot.img image and I have since turned off the phone does not start anymore it remains on the logo infinix

You shouldn't have install update on rooted phone, the phone is bricked now you must flash stock ROM. 
Did you take note of the build no. before it get bricked?

[sergedouai]

Whats is it

[hovatek]

Whats is it

Download the stock rom @ https://forum.hovatek.com/thread-19956.html and flash