mkrest.exe is an application to create a rest file for your phone, if you don't have that rest file, your phone will not start up when you apply patch. it is simple tp make the rest file, just drag and drop your main file over the mkrest.exe, the rest file will be created in the c:\documents and settings\user\ folder. you'll find mkrest.exe in the setool\mk_rest folder and you need to copy the created rest file to setool\rest. that's it