Refurbished monitor won't turn on

I purchased 2 refurbished monitors on July 8th '24 (11 days ago). I received my computer 2 days ago, so they've only been in use for 2 days. One of them works fine, but the other immediately started showing signs of problems out of the box. The first time I tried to turn it on before I received my computer, nothing happened, but worked the second time so I thought maybe I didn't plug it in all the way. However for the past 2 days since they've been in use, the monitor first wouldn't wake up after the computer was turned on from sleep mode, nor could I turn the monitor off (the power LED was on but pressing the power button didn't do anything). Only unplugging it and plugging it back in would get it to turn back on. Now it won't do anything at all other than illuminate the power LED. The monitors backlight is intermittent, and there's no signal from the computer at all. I've tried swapping cables, changing settings, resetting the monitor to default settings (when I was able to turn it on) and nothing worked. I need an exchange for the defective one.

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