Got it, thanks for taking the time to help with this @beegee, I hadn’t done the UF2 mode first. Once I did this, it failed the first time, then worked. I thought the UF2 mode was simply to look at the text file to check version of bootloader. The github link you gave earlier doesn’t indicate this either, might be handy to add?
Another quick question, there was no download option for the .hex file on Github, so I went up a level and saved the target…possibly why it failed? The only other option would be to copy the contents, paste into notepad++, and save with the same name?