Back to square one means having to start all over again.
* Back to the beginning.
* If you are back to square one, you have to start working on a plan from the beginning because your previous attempt failed and the progress you made is now wasted.
1) Negotiations have broken down, and it's back to square one.
2) We lost our appeal of the lower court decision, so back to square one.
3) We thought everything was settled, but now they say they're not happy with the deal, so we're back to square one again.
4) If this guy rejects our offer we'll have to go back to square one and start the whole recruitment process again.