I've seen a couple of devices with black screen after the Teams Splash screen.
One of them was a ThinkSmart Hub 500, and even using the USB recovery procedure didn't fix it - actually it made things worse (cannot login as admin any more). I don't know about this case as much as I didn't factory reset it myself.
Another ThinkSmart Hub has the same issue, haven't factory resetted that yet (would have to be onsite for that), but have tried all the suggestions found here:
https://docs.microsoft.com/en-us/microsoftteams/troubleshoot/teams-administration/teams-rooms-app-wont-start-after-update
also done multiple reboots and the MTR has had a long time to wait between the reboots.
Oh, and doing the step 3 doesn't complete. The MTR is affected (app installed under NT Authority\System), but after creating C:\Rigel\AdminHookScripts\Logon.ps1 and rebooting (multiple times), the file still exists in that location although to my understanding it should be deleted after it is run once. So I doubt the app itself is deleted either.