For Infinix Hot 4 X557-H807AD-N-171110V163 (Nougat), use Miracle box + loader to flash Philz recovery and preloader.bin from your firmware dump using the guide @ https://www.hovatek.com/forum/thread-14106.html (flash 3 consecutive times, then boot straight into recovery mode)
How to root Infinix Hot 4 (X557) after upgrading to Android 7 (Nougat)