There were several ways for a ship to contact another ship.
If the wireless had broken, nobody would have come to help the Titanic until another ship stumbled upon the lifeboats floating in its path.
The transmission of telegraphs did not show a large gap so it might be that the "break down" was possibly made up.
A sextant is used, along with a chronometer and a nautical almanac, to draw lines of position from several stars, that fix a ship's present location. That would have been impossible to plot from a lifeboat, and wouldn't have been any help, anyway. Telling north from south would have been simple, just based on visually observing Polaris on the clear night.Another thing that would have reduced the survivors' chances is that it seem nobody though to take a sextant and Nautical Almanac in a boat. Given these aids, a capable officer could have organised the boats, ensured each had adequate rowers and headed for the eastbound shipping lane south of the wreck. All that was needed was the latitude The wind was favourable and they might have made it.