OK. So I had a similar issue with my machine with the spinning dots after the Microsoft logo with spinning dots disappeared.
The ProgramData\Microsoft\Windows\WER\ReportArchive had several folders but the most recent was
NonCritical_Update;ScanForUp_{bunch of other numbers}
The file Report.wer had EventType=StoreAgentDownloadFailure1
So looks like an update issue. I disabled the Windows Update Service. Follow these instructions carefully.
regedit
Select HKEY_LOCAL_MACHINE
File - Load Hive...
E:\Windows\System32\Config\SYSTEM
SYS
HKEY_LOCAL_MACHINE\SYS\ControlSet001\Services\wuauserv
Start should be set to 3 to disable set this to 4
On the left side move back up to highlight HKEY_LOCAL_MACHINE\SYS
File - Unload Hive...
Yes
Restart your machine.