I usually give my seedlings around 10-15 DLI so I don't think it's light burn. If it's LED 20cm should be more than far enough. Make sure you have high humidity, germinating/seedlings like around 65-70% RH and temps around 26-27°C. Don't water too much, at this stage the plants drink from the leaves quite a bit as the roots are developing.
Side note, you should get a diary going, the community can give better help.if.you give us more info 🙂