Our hero is worried because his phone battery is down to 50%. He must also find a way on how to get through that pile of wooden dicks. I he thinks that fire is the only way to clear those wooden objects. There are 3 techniques he could try to make fire. First is to use the two wooden objects together. Second is to rub 2 rocks/stones. And the third is those coins that are made of unfamiliar alloy. If that "unfamiliar" alloy is a "magnesium" alloy then it can be use to make fire by rubbing them together.
If our hero can make fire, then could use it as a light (preserve the 50% battery of the phone) at the same time could clear the path to deeper part of the larger cavern. And also he could warm himself because there is fire.