HEX info for docx files

My brother has a external drive full of docx documents that are corrupted. According to him, his office got hit by a trojan. I’ve tried 5 of the recovery programs online. None of them have worked. I was chatting with a support tech for one of the programs and he said the document header was corrupted. After a little more research I downloaded HxD and opened the file to view the hex. Can someone tell me what I should be looking for to fix the document header so I can open them? Unfortunately he does not have a backup for these files and they are pretty much every case he’s ever worked on. Any help would be greatly appreciated.