I just received my 798c SI and installed it in the boat. Today I tried to update the software from version 4.51 (came w/ unit) to version 4.780 which i downloaded to my SD card. I followed directions per page 78 of manual. Shut unit of, installed card and turned unit back on. It prompted to install update, yes, abort, no. It then proceeded to flash screen stating it was updating and do not interrupt. This went on for over 1 hour. Finally I shut unit down, removed card and started unit. It stated that it had original 4.51 version in unit. I tried same procedure 2 other times w/ same result. Can anyone tell me what is going on? Any help would be appreciated.