Automatic Cat Toy

When it first arrived we were pretty happy with it. We set it down immediately out of the box and it had enough charge to go. Our cats immediately played with it and everything seemed great! A few minutes later we turned it off and set it aside to charge to full. After charging we turned it on again and... one wheel wouldn't turn. We've got all hard flooring but we tried the high power / carpet setting and it worked, kind of. Spent some time troubleshooting, there was a lot of hair building up on the wheels so we removed as much as we could. Eventually contacted the seller to explain the issue but after a week with no response just submitted a return & replace request. Second unit arrived today and I immediately charged it to full. After testing it a bit I set it down for the cats to play with and left it alone for 20 minutes. Came back to a blinking red light and I tested it only to find out... one wheel was barely moving. It's a little more mobile than the first unit but since one wheel is much slower it tends to just stay in one spot and spin in circles. This time on the high power setting it works well enough that our cats still play with it, but it's clearly struggling and I'm not confident this will last. Update: After more testing the second unit is working fine again. Really nice when it's working. Hopefully it lasts!