Buy only from reputable sources: directly from Waveshare, or from established Pi and electronics specialists such as ThePiHut, Digi-Key, Mouser, CPC, Farnell, etc. I am not endorsing any.
Amazon can be fine, but only if the listing is sold and shipped by Waveshare’s official store or a known distributor, not a random third-party seller. The specialist shops above are the safer bet. You may pay a little more than a general marketplace app, but you get genuine stock with correct firmware and avoid exactly this problem. Two bad units from the same app-store seller is a clear signal to move on from that source.
You might also move to the DSI version. Less hassle, just plug and play.
If you want to size up, 11.26 inch, hdmi but also plug and play and a lot of settings via OSD.
