Well in the end I solved it, I took those two files that were sent via FTP from my other PS4 slim with firm 5.05 and copied them to the PRO. After writing my previous post I came across a compiled version on the internet and when I tried it it didn't work either, but I realized that for some reason those two files weighed differently than mine, so as a last test I decided to replace mine with those and it worked the first time.
I attach the source that I have cited, where the files that do work are, if I can't put hithub links here, then let a moderator delete it. Luck.
Edit:
When sending the post, it no longer allows me to attach the link, so I am attaching a zip with the two files for whoever is interested.