well i just solved this issue by removing folder that called "UpdateService" remove C:/ProgramData/Dell/UpdateService install .NET Core Runtime v5 dotnet 5  Download and install Support assist 
i got error while install SupportAssist  Device Alienware Llienware X17 R1OS Windows 10 BUILD 19044 here is some error result inside C:\ProgramData\Dell\SupportAssist\Agent\logs\installer.logERROR Dell.SupportAssist.Client.Utilities.RegistryUtility - HKEY_LOCAL_MACHINE\SOFTWARE\Dell\SupportAssist ProManage : Not exists ERROR Dell.SupportAssist.Client.SupportAssistInstaller.AutoUpgradeHelper.SupportAssistInstallerPackage - Some Error occured while upgrading msi SupportAssist Agent : ERROR Dell.SupportAssist.Client.SupportAssistInstaller.InstallSupportAssist - SupportAssist download/installation failed with return code: msiinstallationfailed ERROR Dell.SupportAssist.Client.Utilities.RegistryUtility - HKEY_LOCAL_MACHINE\SOFTWARE\Dell\SupportAssist ProManage : Not exists ERROR Dell.SupportAssist.Client.SupportAssistInstaller.AutoUpgradeHelper.SupportAssistInstallerPackage - Some Error occured while upgrading msi SupportAssist Agent : ERROR Dell.SupportAssist.Client.SupportAssistInstaller.InstallSupportAssist - SupportAssist download/installation failed with return code: msiinstallationfailed   And also from windows event log  Product: Dell SupportAssist -- Error 1920. Service Alienware Client Management Service (DellClientManagementService) failed to start. Verify that you have sufficient privileges to start system services.   i already followed remove dir PCDR SupportAssist also registry but never give me good result, what happend with SupportAssist Application? 
SupportAssist unable to install