You'll need to format data. Then flash rom and kernel, then this after
Can you send a recovery log? What all did you flash when that happened and in what order? Thanks
I checked else one time but not disable dm-verity and fec with format data before installation this rom https://xdaforums.com/galaxy-tab-a/development/rom-touchwiz-port-oreo-8-0-t3792635 . Sorry.