I keep seeing the same solution and it keeps not working on my Note 10+ with TMO. This is so irritating. And some of us don't have extra SIM cards laying around to pop in and out.
I thought it was just a TMO issue but could be Samsung only device or Samsung on TMO network thing. SMH
I had this error for several weeks on my brand-new, unlocked Galaxy S10e, which came with T-mobile software installed. I tried every proposed fix I could find in this and several other forums and sites.
What finally worked for me was consulting my service provider (Ting, a pay-as-you-go provider that uses several networks). Ting staff Fedexed me several brand-new SIM cards (at no charge). Then a Ting staffer ported my phone number to the new Sprint SIM. Since switching to the Sprint SIM--through restarts--I have no problems with the notifications.
I heartily recommend Ting, which has very responsive customer service and helped me solve an error many other experts (including several Samsung staffers) were not able to correct.
I have time trying by all the methods found here to solve the OMADM problem and nothing that works. Yesterday the software of my note 10 was updated again and the problem persists. What I have not found is effective comments from Samsung suggesting an effective solution, which shows that this problem that affects many has escaped their hands, but that without a doubt it left the Samsung company through its inevitable updates of systems. <edit>
I have an unlocked note 9 on t-mobile. I have had luck getting rid of the 407 message until next restart doing the following:
1. Turn off phone
2. Take out sim
3. Turn on phone
4. After phone loads, insert sim.
I don't get the hourly message that firmware upgrade failed anymore. But last time I restarted my phone it came back. I don't restart too often, so it's longer relief than any of the other "solutions" offer.
I am having the same issue. I contacted Samsung support and they said to take it to my local Ubreakifix store and have them take a look at the software, so I did but they couldn't fix it, so now what? I'm so disappointed at Samsung support that now I am seriously thinking of going back to iPhone, as a previous iPhone user I can say that apple has superior customer service.