How can you check to see if your supply is defective

Hey LEAFY86! Check out the steps
here and see if they help out. Let me know how it goes!

Make sure you have the correct power supply for your xbox. And then check to see if there is any light on the power supply. If there is no light then it could be an electrical problem. If it has a red light on the power supply that means it is defective
and it needs to be returned. All i can recommend is try other outlets or get another power supply.

Hi!

The reasons could be many. You can try to change the external power supply (maybe it's defective), or it can be a problem of swollen capacitors and in this case you will have to open the console to see and replace them.

Try to change the power supply (or the power cord) first and try to turn it on.

I recently purchased an original model Xbox One and a power supply separate, second hand. Both sellers claimed their items were functional, and I'm tying to narrow down what needs to be replaced/returned/repaired.

If you say "both sellers", do you mean you got the console from one seller and the power supply from the other?

If so, how can one seller claim the console worked without power supply, and the other seller the power supply worked without console?

I have my original Day One Xbox One still in working order. So I can't say that there are specific "weak points" that I could recommend to check.

But since you say you're going to a game shop anyways, I'd recommend you take both console and power supply with you, and have them check their known working power supply with your console, and your power supply with their known working console.

Then when you found out if your console or power supply isn't working, you can then return the defective item to the seller.

Or have them give you the console/power supply pair that they claim "worked".

Can you check your power supply and make sure it is still working? You should see a light on the power supply. I would check the cord from wall to power supply and then the cord from power supply to the Xbox 360. Unplug all of them and reset all firmly.
You can also check the AV Cables as well while your at it. The power supply should have a light showing its working and then pressing the power button on the Xbox 360 should turn it on. Next would be to check the controllers