I had a failure with Spektrum, until I found out it was the ESC that caused it and not the TX/RX. Most RX/TX "failures" stem from some other cause and are unrelated to the actual radios as the cause.
OOPS forgot to charge the battery, or the pack has reached OOL. Poorly connected pushrods, metal on metal vibrating, etc. can make it appear to be a radio issue. But the best one I found was not using a clip on the battery connection and having the pack disconnect on a high G maneuver. There was a very nice P-61 that ended its maiden flight that way.