I followed instruction at Dreamboxupdate,installed latest image(20110905/DM500HD) with Dreamup 1.3.3.7 and I get this message
1:53:00 PM box type: DM500HD
1:53:24 PM Calculating checksum...
1:53:24 PM Uploading file to box...
1:53:37 PM box is flashing from its memory...
1:53:39 PM Flashing failed (!!! 010 INVALID IMAGE (OR OLD VERSION)), box will be unusable now!!