From this post you get a good BLU G91 max Firmware Flash File official stock ROM tested 100% and approved perfectly from the source BLU G91 max Flash File with flash tool, USB driver, and how to flash it
Blu bold spec
6.8 FHD+ 20:9
Infinity Dot Curved Display
1080 X 2460
G91 Max is the best gaming smartphone in BLU’s line. Blazing 2.0GHz Octa-Core speed, the Mediatek helio G95 ARM Cortex A76 processor offers state-of-the-art performance with little competitors. Advanced ARM Mali-G76 GPU ensure high FPS gaming action.