I have some additional information regarding a suitable chassis/adapter for firmware update:
The signal line for Dynamic Power Control (DPR), located on pin 25, must not be attached to GND, when doing a firmware update (or when issuing the AT!BOOTHOLD) command. Otherwise the EM7565 comes up in normal mode, instead of the download mode.
In the chassis I mentioned above the DPR signal was set to GND via jumper (default from stock). In contrast, the M.2 to MiniPCIe adapter leaves this pin floating.
Removing the jumper connection did the trick for that chassis and the included module comes up with PID 9090 instead of 9091 after issuing AT!BOOTHOLD.
Maybe the information about this behaviour might be included into the manuals and release notes, as I didn’t find anything about it in those documents.
Regards
Robert