If I turn it off the red light goes solid for a few seconds as normal...but then the 3 flashes starts showing battery charge and it will keep showing this intermittently all day and night until flat. If I hold the button in for 6 seconds the red light went on permanently until I tapped the button again and its back to flashing the charge level.
I can put it into wifi mode but again if I turn it off from there it still seems to be on.
Any ideas on fixing it ?

The 6 seconds puts it into 'Safe Mode', which is used to updating firmware.

You need a 3 second press to turn it off. Is that what you are doing?

www.motion-gps.com/motion/documentation/first-start-wireless-mini.html

The solid red light is safe mode/firmware update mode, (not a solid green light) , so good you can get it to that, it does sound like it needs the firmware update

before you put the mini into safe mode, have the firmware file from the motion-gps website downloaded /saved to your desktop files

Then put the mini to safe mode/solid red light,
then paste this web link into your browser, 192.168.0.1/

and press enter, which should open up the minis webpage, showing option to update firmware/choose file/select the firmware file pre-saved to your desktop files

sailpilot said..
Thanks Guys, I appreciate the help,
OK, progress but still not right. I did the firmware update, it said 'Success' and it will restart. It didn't actually off and was flashing 1 red every 10 seconds continuously. I let it run out of battery and recharged it, but it was on again once it got charge...without turning it on. Have redone the firmware and now have the same 1 red flash every 10 seconds. ?
Any more thoughts. Thanks

Bin job 😂