apologies for the multi-post. just had a thought about:
you can usually press the esc key to remove the splash screen when it begins to show. you mentioned seeing
that is what i am referring to. if your system will allow you to do that, you may well see the part in the boot process where your system is getting stuck. taking a photo with a phone (or whatever you have. it just needs to be clear enough to read obviously) and posting that could also be helpful.
network failure could be dealt with after boot. login is a different problem entirely and logging failure points to a certain level of brokenness that would make me think about reinstalling.