一着不慎满盘皆输

一着不慎，满盘皆输:

Literally means:

one careless move results in the loss of the whole game

Actually means:

着means the move of a chessman. 慎 means care, and 盘 refers to the chessboard with grids on it.

This phrase means that one will be mistaken to the end because of one mistake made in the process of doing something, which will result in the loss of the whole thing. It is often used in exhortation.

着，下棋时下一个棋子或走一步；慎，小心；盘，下棋用的盘状容器，上面画着规定的格子。

一着不慎，满盘皆输，比喻关键性的一步走错了，就会一错到底，造成全局失败。多用于告诫人们。