Do you have owner's manual?
It's possible you went wrong direction on adjustment. Typically you have force adjustment and closed position adjustment. It sounds like closed adjustment might be off. It meets floor and tries to drive beyond that point, which sensors interpret as an obstruction and since you don't want to squash the cat, it reverses.
Might also be something hanging on door somehow breaking safety beam at bottom of travel, or beam thingies might be loose?