I recently had a problem with a Crossfire nano RX with the same symptoms (first RC failsafes, then the loss of binding). My theorie is that it partially unsoldered itself due to a combination of high power, low airflow (inside heat shrink tube) and I sometimes even used it without the antenna, which wasn’t smart.
I could fix it with a heat gun to melt and re-set all the solder joints on the board.