I am sharing my experience for the redmi 6a cactus smartphoe which has a problem with the eternal hank logo, bootloop and even hardbrick can be solved with this firmware, you can use sp flashtool, Infinity CM 2, etc and bypass Mct. And it works for the dual sim redmi 6a, for the single sim redmi 6a haven't been tried
complete steps can use this method
cactus_global_images_V9.6.11.0.OCBMIFD_20180726.0000.00_8.1_fix_all
complete steps can use this method
cactus_global_images_V9.6.11.0.OCBMIFD_20180726.0000.00_8.1_fix_all