I've been rejected by Microsoft..

I just wanted to put in my two cents from my personal experience on a very similar situation I had years ago.

I used to belong to one of the Microsoft technical forums and found myself in a similar situation where I was being blocked. Couldn’t get access to the account I was using on there. I kept trying to contact Support and explain them what was going on that for some sort of security violation, I was being blocked and I needed my account unblocked or I need an explanation on what I did which I did not do anything and I can say that 100% unequivocally. I was put into a maze of people referring me to supervisors and never being able to connect me with any security division that could unblock an account let alone an IP address. Those sorts of things are completely and thoroughly automated, and there is no person within any company that can fix something like that. I eventually had to dump the account and create a new account which I don’t think I ever bothered doing.

if you are using a dynamic DNS, there should be no way for your IP address to be permanently blocked and if the procedure of releasing and renewing the IP address through the IP config command doesn’t work you need to specify that to Microsoft Support or you might just want to try using a VPN which will further scramble the IP address and possibly get you in with much less stress.  When contacting the support team for the office account, you absolutely must stress to them specifically that it is not a matter of not being able to log into the account it is that you cannot even get access to the login page itself and tell them that since you cannot even get the page to come up, there is no ability to even try to reset any passwords. One last thing try to pin the analyst and or supervisory analyst down to stating specifically to you that this is something that cannot be fixed because that may very well turn out to be the end result, and you need to have them state that to you specifically so that you can stop spinning your wheels needlessly. Before contacting their support, I would give the suggestion of using a VPN a try if you have already tried the release and renew process.