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I am sorry to hear about this situation.
Until/unless the landlord actually evicts you, they continue to owe you a warranty of habitability. See HERE and scroll down to "Texas." This includes not cutting off utilities or electricity. So arguably, what they did was indeed, wrong.
1) If one intends to stay (and fight the eviction), one wants to go to Court and get permission to cut the lock. Doing so otherwise via self-help without the court's order is improper. If one intends to leave in 3 days, one may still technically (counter) sue for this violation, although it may be so minor so as not to warrant the court's time if this is 3 days or less.
2) The owner and the manager are the "same," in that the manager acts as an agent for the landlord. In the end, the landlord is the responsible party.
3) You can call the power company out and they may cut the lock as part of restoring power. If so, then the landlord would have to pursue them, not you. However the police are unlikely to get involved in such a matter as it is civil in nature, not criminal.
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