Hi @Anonymous User
Bit of a long shot have you tried holding in the small reset button underneath the bottom of the NowTV 4K box for about 20 to 30 seconds in an attempt to factory reset it.
Where did you purchase the NowTV 4K Smart box from, was it direct from NowTV or from an Authorised Retailer.
If it's from a third party retailer then you will need to get in touch with them, should it be NowTV direct from their website then try this link below for their live chat web service.
To reach live chat open the link below, then click on the small green arrow below How to Get in Touch, then select TV then click the green live chat button.
Should live chat not load or open for you, then try a different internet browser with it's ad blocking software disabled (MS Edge works for me when contacting live chat).
https://help.nowtv.com/gb/get-in-touch/orders-returns/i-want-to-return-a-device