I emailed the return label with instructions to you yesterday.
Regarding the t-glase: I replied on June 9th with inventory information and options on how to proceed including changing color or cancelling the backordered color, but have not heard back. Unfortunately the value of the backordered t-glase is less than half of the value of the parts you're looking to exchange, so holding the filament until the parts are returned wouldn't work.
Another user who was unable to flash new firmware on his Duet WiFi and reported a similar problem running Bossa 1.8 managed to flash the firmware using the command line version of Bossa 1.8. I had suggested the following command line to him:
It's not uncommon to get a short inside the heater cartridge between the element and the case. This puts the hot end metalwork at 12V or 24V, and if that shorts to the thermistor ground lead then the VSSA fuse blows. If the piezo is also in contact with the hot end metalwork it could also account for your recent issue. So I suggest you check the heater cartridge.