Please, I have problem flashing any firmware on my P88. First time I did it 2 weeks ago went all ok without any issues. Now when I try the same firmware or this TNT it got stuck on step when it starts Verification Checksum, right away on beginning, and I don't know how to continue

I tried the RK Android tool to erase nand IDB, it passed ok, then again Batch tool, select img, will do lower format ok, connect ok, it will download to 100%, next step Checksum, and error right away on 0%, same like in my picture.
Really don't know what to do next, is there some way to unbrick my device ?
Thank you very much for all help.
