Today SDL Tridion CME stops to load with the following error.
/WebUI/Models/TCM54/Services/Lists.svc/GetListEnumerationValues failed to execute. STATUS (404): Not Found
Looking at the error, it seems like setup issue.
Most probable cause is authentication setting for IIS, it should be set for anonymous authentication and disable all other authentications.
Beside that, check the setup steps given as part of answer for the question on stackoverflow: Stackoverflow link