I'm not a lawyer but I suspect if you inform the PM they are not to step foot on your property, if they do so to take back equipment, that would be criminal trespass and theft.
If they are under contract entitled to get back the equipment then their proper route to reclaim it must be through the courts. Your contract may SAY they have the right of access, but I don't think that the civil law (the contract) supercedes the criminal law (barring them from your property). If you deny them access, they have LEGAL recourse to sue you, but they just can't come and take stuff--they have to establish that they are legally entitled to it and have the court award it to them.
But it really looks like you need a lawyer who specializes in this kind of dispute.
Contractors toss out legal threats because they can usually bluff the homeowner. The con does this everyday, the H/O doesn't (been burned once) so the H/O can be intimidated, especially with "builder's liens" and other threats.
"I've had my law firm review it and you have to do such and such..." is very typical first-volley bluff. Sounds good, but it's most likely another attempt to intimidate you. Of course, it may be real, but since this is a big job, a BIG cost to fix, you need proper legal advice.
Find a good lawyer and do what he/she tells you. Or expect to lose more money and not get the job you want.
Sorry to be blunt, but I call it the way I see it.
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