When in desktop mode, the power button will turn off the screen but not put the system to sleep, so you could switch to desktop mode for long downloads.
Also, modern OLEDs are very resistant to burn-in. You could probably leave a static image on the screen for 24 hours a day for several months before it would be noticeable.
If you post a copy of your
docker-compose.yml
file inside a code block, somebody can probably identify the syntax error for you. Otherwise, the best I can do is tell you you can paste your YAML into https://www.yamllint.com/ and it will tell you if your YAML is valid or not.