Hi!
I built LO 5.3.0.0.alpha0 yesterday on Ubuntu 16.04. I also have 5.1.4.2.
It’s my first time building anything on Linux and it went well. I ran the new build of writer once after installing.
Now i don’t know how to run it again.
Open terminal and enter: XXXXXX/instdir/program/soffice (where XXXXXX = your install/build directory) to start the LibreOfficeDev main screen. From there you can open Writer, Calc, etc. OR enter XXXXXX/instdir/program/soffice --writer to specifically open Writer.
Thank you!