I downgraded my firmware successfully from 1.8.1 to 1.6.8 one version at a time ( per instructions) but when I got to 1.5.7 it was successful but I had an abnormal compass message. Even after I recalibrated it. Then I noticed that there were two 1.5.7 bin files from the site. One was about 63mb and the other only 7mb. So, my Question is . Do I need both ? and do I copy both to my root SD card simultaneously,or do you install them separately ? And , is this the reason for the abnormal compass ?