I'm experiencing the same issue.  Using a Samsung Galaxy S9+.  Already, I've uninstalled/Re-Installed the DJI MIMO App.  When trying to register, a pop-up appears stating "Network Error".  So frustrating!  I was really excited to the Osmo Mobile 3.

   I switched my Wi-Fi from 5Ghz to 2.4Ghz, and I was able to connect.  The Bluetooth keeps disconnecting/re-connecting, though.  Next thing to troubleshoot.  

I had the same activation issue using the Mimo app on my ASUS Zenphone.  It connected to the Osmo Action, but no matter what I did, it wouldn't activate.  I then tried with my wife's old Moto GPlay phone, and after installig the same Mimo app, it worked.  Who would have thought?

PlanJ Posted at 2019-10-23 15:36
I've received the OSMO Action yesterday and I tried all the method above to activate it but failed..
It shows "Factory Mode" on the screen, and I dont know how to exit this
can you please give me an advice how to exit this and activate it?

I just purchased Osmo Action last week and mine is also not activating and shows factory mode. What did you do to fix problem?

I've been considering purchasing the Osmo Action for vlogging purposes; however, am I to understand that you need to own a smart phone to activate this device? I do not own or use an Android or iOS device. Will this prevent me from utilizing the Osmo Action? Can anyone answer this please? Thanks, in advance.

Buongiorno a tutti, ieri mi è arrivata la nuova DJI Osmo Action. Ho già letto che per Android, in una prima fase non funzionava il collegamento con l'app, ma sopratutto noi Italiani dovevamo cambiare i gigahertz nelle impostazioni della action cam, ed abbassarli al di sotto dei 5 ..  Ma a parte questo vi spiego la mia situazione....

Accendo Osmo Action, i primi minuti li ho utilizzati per capire un po' i menù dell action cam, tralasciando gli avvisi per connetterlo all'applicazione. Passata qualche ora, scopro della modifica da fare all'action cam, ma ora, nel momento in cui accendo il dispositivo l'immagine del QR Code si ferma sulla action cam non facendomi cambiare più le impostazioni, per cui non posso connettermi all'applicazione

timesnaps Posted at 2019-5-20 07:54
a colleague tells me her Action Cam became useable without activation, by simply connecting the USB charger and taking out the battery, then pressing record. Hers is working ever since! might worth a try...

she is such a liar

I get error "Activation failed" again and again on activating the osmo action camera.
I have downloaded the latest version of firmware and updated by microSD, but error is staying.
DJI Mimo iOS 1.3.2 + iPhone 8

How I can activate camera by computer without using DJI Mimo?

Best of luck, fella. I can't even access the Osmo Action Screen since the App won't install, and the OCR code expired, with ZERO possibility to activate AT DJI WEBSITE!