My plane went in. Incomplete log

Flying the other day when I lost video. My plane went in. When I got to it the battery was still plugged in and measuring 20v I am running 6s li-ion. My log quit recording the same time My video went out. I originally thought I lost the battery. Log says batt was 16v. when it quit recording. I was in a hard left turn when I lost everything. My failsafe is set for rtl. When I flipped the rtl switch. It showed in the log then it went engaged, but the last mode in log was fbwa. Gps speed was at 40m/s at time of video loss. When retrieved the plane It was upside down and in almost perfect condition. It seemed like it landed itself but why no log for that? So Strange.