If it died, the route was not saved. Make sure to verify the battery level, and charging the device, before starting the hike. If you see the battery is low, save the first part of the hike, and start it anew - in that way you'll have at least one part of it, should it happen that the watch dies again.
Hi yeah phone was full but left camera open in my pocket, so it did save up until phone died, but it just looked like we had walked to the top of slieve bearnagh and stayed there
Ah, sorry, I misread your OP - I thought it was the watch that died. Did not see it was the phone instead. However, if you have a watch without own GPS, relying on the phone's GP, then it is comprehensible - it cannot record any position, if the phone does not report it.
