The latest firmware version is available through the Evo app and Ozobot Blockly.
Multi-bot via the Evo app only:
https://ozobot.com/multi-bot-update-renaming-using-the-evo-app/
https://www.youtube.com/watch?v=ys8t8LjkPkc
Single Evo via the Evo app:
https://ozobot.com/updating-your-evo-robots-with-the-ozobot-evo-app-2022/
Single Evo via Ozobot Blockly:
https://ozobot.com/updating-your-evo-robots-with-ozobot-blockly-2022/