The easier way to use the Universal Flasher is via PRSCustomizer, details for which are in this thread -
https://www.mobileread.com/forums/showthread.php?t=27177
However, I'd suggest not doing that until you're reader is working correctly - instead, I'd suggest trying a reflash of the 'official' flasher. The issue you'll have will be that it'll say it's up to date, so what you first need to do is to rename the .exe to .zip, unpack it, edit the file 'prs505/eBookUpdater/assets/updaterAssets/PRSVersion.dat' so that 110018040 reads 110018041, re-zip, rename to .exe and then run it.