If you are in return time go back to the store where you bought it and return it and buy another one again.
Otherwise bring it to a samsung costumer service to have them flash them software.
Let me know
Thanks for your reply - I bought it direct from Samsung. I don't know where a Samsung customer service is or if I'd be able to go there (because of coronavirus), I am hoping there's something I can do myself. I haven't tried a factory reset but that's an idea that's occurred to me.
Anyway, I wondered if there were any quicker things to try?