Can't make boolean mesh


Hi everyone, this week i faced pretty weird problem with booleans. I have a helmet model which has 20 millions polygons and want to make unified copy of it, when it finishes unifying mesh, it just says that it created new tool but with certain errors, but nothing appear in tool menu. Or in some cases it even says that some of my subtools have issues and the program can’t start calculating my mesh. I tried to check coplanar and issues, tried to make boolean from different subtools and even tried to remesh every subtool for this. Nothing happened as you see. Here i attach the file for you. Thanks