"The code is more what you'd call "guidelines" than actual rules." - Captain Barabossa
It sounds to me like you've got quite the predicament, and you are trying to hold to some unreasonable ideals.
I've stressed to the team the benefits of self-organizing teams and team empowerment.
Explain to your children that self organizing and empowerment does not mean they get to do anything they want. If your team decided to go steal some automatic weapons and rob a bank, you aren't obliged to follow through with them just because they are empowered.
They cannot "fire" you. That is the role of your manager. Firing always comes from up the chain, not from below. Sure, they can jump rungs in the hierarchy and work with your boss to remove you, but since apparently your boss and your bosses boss are both on leave without having put anyone in place in their absence, there's not much of a hierarchy to go to. You've got a few months.
I told the scrum master that I'd like to talk to the team about this, but he was firm that they felt "intimidated" when I was in the room, and didn't want to discuss it with me.
Well that's just too bad for them. Talk to them anyway. Self empowerment may give you the ability to make your own decisions, but it doesn't free you from the responsibility to live up to those decisions. If I had a team like that, talking to them would be the kindest level of response I'd consider.
One might say "Oh, but the SCRUM master is supposed to resolve impediments like this. Everything should go through him." Well tough. He screwed that up when he went to you to tell you you were fired and failed to do so in a sufficiently courteous way that you accepted it. A SCRUM master is expected to have better people skills than that.
So what do you say?
First, you want to find out if they actually decided to "fire" you. You have one person's word on that, and I do believe this is the kind of situation where the team should be able to directly say their piece.
Second, consider what "firing" means. You claim to be a hands off manager, but they want you gone. Understand why. They aren't writing the paychecks, so the decision to fire you isn't a "oh they're not pulling their weight" kind of decision. That's a "this person is actively getting in the way" kind of decision. Something really isn't adding up here. You need it to add up for you before you make any meaningful decisions. Being an anonymous person on the internet, I can't say if its you or them or the SCRUM master, but something is really really really wrong in this scenario, and you better know what it is by the time you're done talking with them.
Work with them. Be a manager. Find a way to solve the problem. Find a way for you to be able to do your job, while they do theirs. Make it happen.
Now, if their answers provide you with sufficient closure to honor their self empowerment, now you have to show the team what happens when you "fire" leadership like that. Say "Fine. I'll stop acting as your manager. You can't actually fire me, because that's not your position, but if you want to play this game, we can play. I was your manager, helping insulate you from corporate politics and the stress of reporting to upper management. Now, I am your upper management, and you no longer have that insulation. Now since I can't actually remove myself from this position, I will instead simply begin relaying tasking from on high." Explain that just because the team voted, that doesn't mean you don't have obligations to upper management that you have to fulfill, and will continue to do so.
Then, get help.
A mutiny is not a small thing. Your entire team just voted you off the island. Don't underestimate it. Get ahold of someone above you to help. Maybe you call your boss on leave. Maybe you talk to your CIO. Someone needs to know that there is a major people problem in your company, and that you are solving it. The second half is clearly important. Never go to leadership with problems, go to them with solutions.
The solution I would recommend is to craft your image as the "manager bearing requirements" by choosing things to require which leadership (i.e. CIO) would want, which is crafted to build some self-realization to go with this self-empowerment. They may think they're free to do what they want, but you are still obliged to make them a successful team. If you have to do it from afar, do it from afar. Find out what about your hands-off approach was so intimidating, and make sure you don't ever do that.
The end goal is to get them to realize you are on their side. If they are truly self empowered, then they need to come to the realization that you are a beneficial part of the team. They will only come to that realization if they are successful. If they get deluged with impossible deadlines and hopeless red tape, they'll never see it.
Just make sure that it all adds up. 2+2=4. A "hands off" manager is "fired" by the new SCRUM master for being too intimidating while two layers of management are on leave? Something doesn't add up from here. You're closer to the situation. Figure out what doesn't add up, and fix it.