I have never updated my Cinemate 520 system, but upon purchasing a new TV I am having issues with ARC/CEC between the Cinemate 520 and the new TV. The first step for me was updating the Cinemate 520 firmware to ensure it is as up to date as possible.
Following the support document, I inserted a flash drive into the Acoustimass module, it deposited the CONFIG file and I used the updater software which placed the update file 1.7 on the flash drive.
The issue I am running into is when plugging the flash drive back into the Acoustimass module, the light eventually starts blinking red and no update was completed. I have tried all the steps multiple times.