If xHP Flashtool for Windows crashes on startup (right after the Splashscreen) you can try installing the following tools and runtimes, which are required to run xHP Flashtool but may be missing on your Windows installation. Please install the tools/runtimes one after the other and check if xHP Flashtool starts properly.
.NET Native Repair Tool
https://xhpflashtool.s3-eu-west-1.amazonaws.com/NetFxRepairTool.exe
Microsoft.NET.Native.Runtime.2.2.appx
https://xhpflashtool.s3-eu-west-1.amazonaws.com/Microsoft.NET.Native.Runtime.2.2.appx
Microsoft.NET.Native.Framework.2.2.appx
https://xhpflashtool.s3-eu-west-1.amazonaws.com/Microsoft.NET.Native.Framework.2.2.appx
Microsoft.UI.Xaml.2.4.appx
https://xhpflashtool.s3-eu-west-1.amazonaws.com/Microsoft.UI.Xaml.2.4.appx
Microsoft.UI.Xaml.2.5.appx
https://xhpflashtool.s3-eu-west-1.amazonaws.com/Microsoft.UI.Xaml.2.5.appx
Microsoft.VCLibs.x86.14.00.appx
https://xhpflashtool.s3-eu-west-1.amazonaws.com/Microsoft.VCLibs.x86.14.00.appx