File extensions are merely "suggestions" as to what app may open the file. Few are more ambiguous than "DMG" and "IMG". Shrinkwrap was infamous for making IMG files that only it could open, and THEN only by using the correct version of their software. Often newer versions could not open older files. All were ending in .IMG, an extension that was used by several other apps at the time, including apple's own fledgling disk utility. Which led to me having to have three different versions of the software on hand to cover MOST of the possibilities.

The next step may be to give us a dump of the start of the file, to see if we can recognize the "magic" at the start.

in terminal, type:
Code:
dd bs=256 count=1 if=


do not hit return. drag and drop the file into the terminal window so terminal enters the full path for you. then add to the end of the line and hit return:
Code:
 | xxd -c 16


it will look something like
Code:
dd bs=256 count=1 if=/Users/falken/Desktop/mydisk.img | xxd -c 16


post the results. please use the CODE tag to format it. This is an example of what you can see with that, viewing a store file here:
Code:
WOPR:~ falken $ dd bs=256 count=1 if=/Users/falken/Desktop/mydisk.img | xxd -c 16
1+0 records in
1+0 records out
256 bytes transferred in 0.000029 secs (8801162 bytes/sec)
00000000: 0000 0001 4275 6431 0000 2800 0000 0800  ....Bud1..(.....
00000010: 0000 2800 0000 100c 0000 0108 0000 200b  ..(........... .
00000020: 0000 0000 0000 0000 0000 0000 0000 0800  ................
00000030: 0000 0800 0000 0000 0000 0000 0000 0000  ................
00000040: 0000 0000 0000 0003 0000 0001 0000 002a  ...............*
00000050: 0000 0003 0000 1000 6277 7370 626c 6f62  ........bwspblob
00000060: 0000 00c9 0000 0000 0000 0000 0000 0000  ................
00000070: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000080: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000090: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................


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