The deploy was refused because the staged volume size (2048 MB) exceeds the Trial plan's 500 MB volume storage cap, which is the error the platform returned when the changeset was applied. The environment is not locked: a refused apply is terminal on that specific changeset, and the environment accepts new changes immediately. To proceed, you would need to reduce the volume size to 500 MB or less, or upgrade to a paid plan (Hobby allows up to 5 GB per volume). Your workspace is also at the Trial plan's 3-volume-per-project limit, so adding both volumes in the current project will require a plan upgrade as well.