back to square one
An expression used to mean that it is necessary to stop whatever one has done on a new project and to start again completely.
EXAMPLE:
When our experimental design for a new solar automobile failed totally on the first day of testing, our engineering department knew it was back to square one.

bag of tricks
The total skills, knowledge, and often secret abilities that a person has (a traditional reference to a magician’s bag).
EXAMPLE:
To be a successful in today’s competitive business environment, an executive has to use everything in his bag of tricks.

blow off steam
(verb phrase)
to release frustration or anger that has been building up; also to celebrate or do something in a loud or noisy way
EXAMPLE:
After a week of negotiations with the union, the workers decided to have a party and blow off steam.