Hi @Alvaro Vinicius ,
Thanks for reaching out to Microsoft QnA.
I understand it is taking a long time for the VM to start after the OS disk swap. However, this is common, and I have seen this before. If the OS disk size is big, it takes longer time to boot up the first time on new hardware. Also, at times there are pending updates which take time to complete. Also, windows OS takes longer to boot up the first time than Linux OS.
You can check the latest boot diagnostics screenshot, and if you see the VM at the login screen (Ctrl+Alt+Del) screen, this means VM has successfully boot up. If it's a Linux VM, then you will understand the VM has successfully boot up if you see the login prompt.
Is the VM now booted up? If not, let me know, and I can help you further on this.
Also, please feel free to let me know if you have any further questions. Will be happy to answer them.
Please don't forget to "Accept as answer" and "Upvote" if you think the information provided was useful so that it can help others in the community looking for help on similar issues.