2100 flash file not flashing

I recently bought ufs3 but the 2100 flash provided on the site is not being
flash to the mobile i asked the local vendor the reason he told to first flash file of lower version and then try for the next higher version can anybody tell me the reason what i should do in this regard

2100 always has been a bitch..

I suggest you do as he said. Probably has to do with minor hardware "change" regarding to soft version.

WBR