I envisage that scene a bit like the standard war film cliche. The scout has just stepped on something that's gone "ping" - and now can't move his foot until someone comes along and deactivates the mine.
I don't see why the bloke couldn't have just sat there with his finger on the button until the end of the day... Or until someone comes along and slides a spring-loaded doohicked under this finger to hold the button closed, until the patrol can get to safety and then mine can go up when they're someonewhere else.