Me. Stat. tit. 14 § 6025

If a tenant changes the lock and does not provide the landlord with a duplicate key, in the case of emergency the landlord may gain admission through whatever reasonable means necessary and charge the tenant reasonable costs for any resulting damage. If a tenant changes the lock and refuses to provide the landlord with a duplicate key, the landlord may terminate the tenancy with a 7-day notice.

4.
Waiver.
Any agreement by a tenant to waive any of the rights or benefits provided by this section is against public policy and is void.