1.
If someone beats up on a person or beats on them, they hit or kick the person many times. (AM)
He ~ my brother’s kid one time.
PHRASAL VERB: V P P n, also V P n
2.
If someone beats up on another person, they threaten them or treat them unkindly. (AM INFORMAL)
She had to ~ every customer just to get the bills paid.
PHRASAL VERB: V P P n