This is a specially manufactured good and you may have recourse beyond filing a mechanics lien for damage you suffer as a result of the rejection of a specially manufactured good under the UCC. There are very strict procedures to follow to remain eligible for recovery. Speak with an attorney as soon as you can.
The content of this message does not constitute legal advice and is not intended to be relied upon by anyone. It is highly recommended that the reader seek the opinion of a qualified attorney in his or her area for consultation and assistance. There are applicable statute of limitations and other considerations that only a qualified attorney can provide guidance on after being fully informed as to all of the circumstance of your particular case.
There is no such 20 day requirement in the mechanic's lien law. You may have lien rights, but there are several factors that go into determining that. You should contact a MA construction law attorney for more details, and soon. The deadline to file a lien is short.
Massachusetts liens laws are very strict. If you are eligible to assert lien rights you must comply timely. Whether the project is public or private my affect the your rights. You do not state enough facts to answer your question. You should consult a construction lawyer promptly to ascertain your rights.