Rekordbox - Windows laptop unable to open database file

Hi I have bought a second hand DDJ800 and installed rekordbox 6.6.1. windows intel laptop. When I click to open rekordbox I get the message "unable to open database file". Then it shuts down. I have never had recordbox on my laptop before. Sometimes the process gets further and it says something like set up new user (a blue button). Then the error just appears again and it shuts down. I have seen lots of unformation about backing up, remaining, copying files from one place to another, rename files. But none of it seems to work. I have uninstalled and reinstalled rekordbox. Restarted the laptop mutliple times. I installed an old version and that gave the same problem. Has anyone come across this and resolved it? I wondered if anyone had the same experience. I have seen some historic posts on here but there seems to be no resolution mentioned. Thank you