Contact support they will give you ftp with the image you require.
will be good if you have the device serial also the type of the device and version image you require
Please call into Support and we will be happy to provide this to you. Thanks.
The two gentleman above are correct, as that is your only choice.
You want utilize that venue for a couple reasons. For starters, your, model of ETM, version, build etc....
I was in a similar situation, and someone here offered to ftp me an ISO they had.
Bad decision and choice on my part. I had G4 boxes, and they had G3, also, different controllers, etc...
Though it can be frustrating, these boxes are so sensitive, you really need to go to support to make sure. I have even gotten an incorrect image from them before, because of a misread serial number.
I know this isn't the answer you want but it's the correct one.
Hope this helps, and if not inbox me ....