Xbox ventilation

Having your Xbox One S in a vertical position(without stand) will effectively block the side air vent. This will cause insignificant ventilation, resulting in the console overheating and shutting down and possible damage.

The Xbox One S requires a stand to be used in vertical position, which will allow proper airflow/ventilation.

You probably need to clean the dust out of it as others have said

If the console overheats and shuts down, this is an indication that your console is getting too hot, and you may need to adjust its placement or remove items that may be blocking vents.If
your console consistently shuts down automatically due to ventilation problems, even after the console is free from clutter and no vents are obstructed, it will need service.Note If
you are using an Xbox One S or Xbox One X console in a vertical orientation, using the proper console stand is required to ensure the bottom vent is not blocked.

Here is a little guide. Also, get some compressed air on the back and sides. Maybe is dust. Here is the proper
use of the vertical stand.

Make sure you use only the stand designed for your Xbox, which helps console stability and operation. Without the stand, vertical positioning blocks a cooling vent. If you don't have a proper stand, put the Xbox as the guide says.

EDIT: If nothing helps you must repair it as others have said.

I actually had the same problem as you. I am not sure if you have the space for it, but I ended up buying a small table for the system to be able to lay it down on from Walmart.