“The user profile service failed the logon. User profile can not be loaded.”
After reviewing the event logs, I found an error:
"Windows cannot copy file C:\Users\Default\AppData\ Local\Microsoft\Exchange Server\V14\CmdletSqmData2292_ 100.sqm to location C:\Users\a-rnavarro\AppData\ Local\Microsoft\Exchange Server\V14\CmdletSqmData2292_ 100.sqm. This error may be caused by network problems or insufficient security rights.
DETAIL - Access is denied."
The fix was that the Exchange .sqm file had incorrect permissions and was causing this event log on attempted logon; I set that file path to inherited permissions, and then was able to log on.