How to replace TV connected to an old Xfinity DVR?

Sound's always been bad since the day I got a DVR box 6 months ago (to allow caption formatting) and now the sound on my TV's fried. Techs report now there's a line/connection problem but due to COVID-19 at least 30 days to fix. I've got the original TV still that will fit into the space available now with the DVR. I also have HBO for first time. (1) If I use autoscan for channels, will the old TV then be able to get HBO (201+)? (its remote only goes to 125, I think, but then so does the TV I'm replacing, and it gets the HBO channels. (2) How once hooked up do I sync the DVR remote, TV remote, together? I gather this would be required. Thanks--I'll go crazy with no TV in isolation.