thanks a lot for the description! I have a similar problem with the USB-C port and one of the SIM cards also permanently loses the connection, so I have to restart the device every 2 days. But before I order a replacement, I wanted to see if I could detect a possible loose connection that I could possible solder. Or do you thin that makes little sense with such small circuits?
Also, how did you finally assemble the device? Does the back need to be glued back on? Is the residue from the original adhesive sufficient?