If you have a mobile hotspot available to you, you can try connecting your TV to it to see if you can get through setup.
If you can successfully get through setup, navigate to Settings..Systems..About and see if you have a MAC address showing. If these are all zeros, then the NIC card (wireless network chip) has an issue (especially if you are seeing no networks at all, not even neighbors. You can sometimes fix this with a soldering iron, but if not adventurous and this is indeed issue, then either repair or replacement is needed. Unfortunately, when dealing with RokuTvs, all warranty is done through the manufacturer of the TV. (https://www.hisense-usa.com/television-1-year-warranty) One year for US, 2 years for the Brits/UK.
If you can get through setup and then start seeing networks detected, could just be a problem with your network setup and maybe needing some router settings verified/changed.
In the event your Hisense has an ethernet port, you can certainly run an ethernet cable and complete setup. (this will bypass wireless issues, but not all RokuTvs have ethernet ports).
Feel free to post update or if you need more help.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102