If a render fails, the credits it charged come back to your balance automatically. The video shows as failed with a short reason. Generate again, or re-roll the failed layer if most of the video finished.
If a render looks frozen, give it a little time first: long or high quality videos genuinely take a while. Chillframe also watches for renders that stop making progress. A truly stuck render is failed automatically and refunded, usually within two hours.
A one-off failure is usually bad luck and safe to retry. If the same brief fails repeatedly, tell us in the chat or email [email protected]. Include the video's name and roughly when it failed, and we'll dig in.