I'm surprised they didn't push back when they said it was out of warranty. They send it in for repair, and it was never fixed. They can either continue the process of trying to repair it, or refund the original cost of the device.
I had a similar problem with Twinkly Xmas tree lights. It was even more frustrating than this because instead of just having me send the lights back, they just kept me trying all these different power plugs/checking with a voltmeter, etc. I should have asked myself “why in the f$&@ am I doing this” when clearly the lights were just dead. After the last correspondence I was busy and waited a month to respond and when I wrote them back they basically said it’s out of warranty, good luck. I pushed back and they couldn’t have cared less. All you can do is tell your friends and write a bad review. Good luck making it slip past all the positive fake reviews!