Currently I am using a mfgtool package downloaded from internet L4.9.88_2.0.0_mfg-tool_MX8MQ.
This can be used to flash 4.9.88 kernel version for i.MX 8 without any problem.
But the same package can not be used for latest images from SUMO with kernel version 4.14.98 sumo.
Could you please share the latest mfgtool package for the same. I am even open to use open-source tool to flash the eMMC provided it works reliably.