Should I be glad or sad that finally I found there are still a few people encountering the exact same problem? I get 32wd_to many times per day. After several kinds of test, removing sd card, reflash emmc and firmware, keep extras-devel and extras-testing away and enable r&d mode to disable watchdog do not help. Now I doubt if a unstable battery triggers watchdog to reboot my device because it seems worse when my battery level is low.