mishandle

Short definition from Wiktionary

Verb

1. 1
   To manipulate something roughly, causing physical damage.
2. 2
   To deal with a situation incorrectly or ineffectively; to make a mistake in handling a situation.

Noun

1. 1
   Rough manipulation which causes physical damage.
2. 2
   Ineffective or incorrect deal.
3. 3
   Improper, wrong, or bad usage or treatment; abuse.