Bought a NEW device that is faulty and T Mobile refuse to replace or refund

I bought a brand new Franklin Wireless RG2100 in December 2023 from the flagship T Mobile store in Las Vegas.  I am in NY and it is faulty.  I took it to a Boston T Mobile store who told me they couldn't do anything as it was pre-paid (bought outright) and to call customer service.  I went to New Haven T Mobile store who told me to call customer service while instore as they had no process to deal with a pre-paid faulty device.  We called customer service who didn't know what to do.  I called customer service the next day and spoke to a supervisor who also said he could do nothing.

I have paid for a brand new device that is genuinely faulty, under warranty and still looks brand new, yet T Mobile have taken my money and refuse to refund me or give me a replacement device.

Nobody disputes the unit is faulty, even though customer service imply they don't trust me, however their own store on the phone told them it was as responsive as a "brick".  What they are doing is nothing short of theft as they know it is faulty, they know it is under warranty, yet they won't give any means to replace, fix or refund it.

To clarify, there isn’t even a light scratch on the device, it still looks brand new and still in it’s original box.