BETA won't Launch

I am entering this error for my cousin, who has an original Xbox One and has access to the beta. Originally, upon installing and launching the beta (MINECRAFT: Better Together (Future Release)) he could play and join servers. After joining Mineplex, playing SkyWars, and then returning to the main lobby and opening chat, he fell through the world and then the game crashed. Now when he tries to launch the beta, he gets to the Mojang Title Screen and then it gives him the following message, which is: "Give it another try. If you keep seeing this, turn off your console by pressing and holding the power button for 10 seconds and then turn it back on and try the action again." He has done this SEVERAL times, however, and has also reset his internet, uninstalled and reinstalled the game, and unenrolled and re-enrolled into the beta. NOTHING WORKS! Please help as he is an adamant fan of MINECRAFT in any form and really, really wants to keep participating in the beta. Thx.