I'm very interested to see what the issue is from this. Please update us when it is sorted as your problem isn't your run of the mill standard ones..... you've had bad luck with this.
Hope you get a quick and fast solution but I can see your phone getting exchanged in the end or you get a full refund. Exchanges or refunds try get them sorted ASAP... I know there are many other things important in life especially in current times... but if a refund or exchange needs to be done... I just like to get it out the way personally... especially if high valued.