Hi Cherokee,
Many thanks for your speedy reply there. About characters that appear during boot, we get the below.
Àü
+SIM: 0
+KSUP: 2
The À appears on reset apply, the ü appears on reset remove (ie boot start). The +SIM: 0 appears after 12 seconds, and the +KSUP: 2 after another 0.3 seconds. The HL7692 is ready to accept commands after 13.2 seconds.
Indeed, when we then type eg ATI, only the TI is echoed back. If we do ATI again, we get:
ATI
HL7692
OK
About using the latest firmware, I’ve been unable to make the 2.27 installer work 
The topic as below has the details. Do you have any insights ?
Best regards,
David