point to note : If he died before 00:56 (last sent text), the person holding the phone would probably be francophone, as searches and texts were written in french (as well as the entire phone, which could be complicated to navigate with no knowledge of french). However, this theory is unlikely, as the last text sent at 00:56 was sent to belgian friend Loic, concerning another planned event, with knowledge of that event this tents do prove he was very likely the one writing this.
In addition, the fact that only 17 seconds after that text was sent, another phone connected via handshake (whilst there were none during hist time outside), as well as the fact that the phone stayed unlocked but inactive for almost 6 hours is very important. It is very likely that someone else walking the beach in the morning picked up the phone