x521 MT6735_S00_J5088_LWG_M0_CY_MP_V0_1_5_S160729_1_lwg_n_eMMC Nvram File (MobiFirmware.com)

NVram-Secro_Infinix Hot S Pro (X521) NVRAM (X521-J508H1-M-161202V7) (MobiFirmware.com)

Infinix-X521__6.0 Nvram File (MobiFirmware.com)

Infinix X521 Securtiy Files (MobiFirmware.com)