Not much to go on here but it sounds like you have it set to the wrong source. When you say cable are you using a cable box or is the cable coax directly plugged into the TV? If it's a cable box then you should use the HDMI connection with an HDMI cable and use the box to change channels. If it is a cable directly connected with coax then you should use TV or antenna as your source. With a direct connection you probably won't get 1080p HD or 4K UHD pictures, most likely 720p, since that usually requires a cable box and an upgrade tier.

I've gotten mold on the latex caulking and I used a thick toilet bowl cleaner with bleach. The thick type makes it cling to the area and you need to wait about an hour before washing it off. The one I used is Walmart Great Value toilet bowl cleaner with bleach. It worked great.

In the Task manager open the Details tab. Scoll down to find what process is running at a very high level. Right click on that process and if it is not a basic Windows function you can end task or set the priority to low. If you can find the process that is doing this (perhaps Runtime Broker) you can see if you can remove the function from the start up. If nothing helps then re-installing or Resetting Windows could fix the problem. In Windows 10, open the settings menu (Start > gear icon) and go to Update & Security. You can Choose Troubleshoot or Recovery > Reset this PC and follow instructions.

Receivers normally have 1/4” jacks for headphones as this Denon AVR-1912 does (not 1/2”). You don’t give enough information for a solution but if the person is mostly listening to TV and the TV has bluetooth then get them a set of BT true wireless earbuds which are more comfortable than headphones. Go to Amazon and search for Boltune Bluetooth 5.0 Earbuds as an example. The Denon receiver can be set up to send the audio to the TV if it is connected with an HDMI cable. When the earbuds are taken out of the case it should connect to the TV and the TV sound should mute automatically. You will have to pair the earbuds with TV before this works but this should be required only once. I don’t know if the audio will come through the TV for other sources such as Radio. but if a cable box is used for TV they usually provide music channels. The receiver does not have bluetooth.

It sounds to me like you have a shorted output transistor or output module that is either shutting down the power supply or blown an internal fuse. You state that all the other components are powered up, what other components are there? Anything external to the receiver would not be affected. One more thing, check your speaker wiring to make sure you don’t have a short. That could shut down the sound.

I would call the dealer and ask if there is a service bulletin about that problem. Also, don’t use the cruise control. You used the word rooms in your post but that makes no sense so might want to correct that.

I’ve looked at two different sets of specs and nothing is mentioned about WiFi so your TV does not have it.

Instead of water, I would use alcohol. for other printers like Canon, the print head may get clogged. Remove the ink cartridge and use a Q tip soaked with alcohol and lightly touch the print head. allow to soak for a minute then dab with a lint free towel (old T-shirt will work). Install ink cartridge.

You might just try going to Lowes or some hardware store. They often carry metric screws.

Power supplies normally have short circuit protection that prevents them from getting destroyed if there is a short somewhere. Possible problems would be 1) defective power supply (unlikely if the part was new), 2) Power supply set to (or designed for) wrong AC voltage (for example set to 115VAC but used on 240VAC). 3) Power line has a lot of spikes that may damage the supply. You should use a transient (spike) suppressor power strip to help eliminate this. It is possible that the burning smell was left over from the first failure unless you noticed something else to show it was failing again (flashing screen, weird noise) . When components heat up, the rising air can bring out the smoke smell)