On working unit we get an inverse question mark, and then after a very short while it goes to boot menu 126.96.36.199 offering to load 1. start operation code 2. start boot menu and after 10 secs it starts option 1 on its own.
On "non working" card, we get 2 inverse question marks for first boot. Then power cycle card, and this time we get nothing - nowt 😞
Any ideas or is there anyway we can force as we have the cable a firmware upgrade or recovery image?
Without being able to access the boot menu there is not a way to force a firmware upgrade. Have you tried re-seating the unit and trying the unit in a different slot? If so then it may be time to look into calling in and getting a case open, it may be a hardware fault.