(I personally dont recommend soundbars, or ONN products, so the two of them seems a match made in hel...errr...Walmart)
As a general principle and practice, I keep all boxing and receipts for everything non-perishable I buy, especially from Walmart, just because something like this can/does happen. (FYI, if you can find some sort of packaging, they can look up the receipt given a CC/DC/card).
I dont suppose this soundbar has firmware that can be updated, and that you havent yet updated, that may magically fix all the issues?
Does this source of ultimate joy and happiness have a name and model #?