To answer the headline question:
(the rest of the points are debatable)
Grab the sd card, and look at it on your pc. If windows can’t read it, do so from another linux (live boot Ubuntu or something on your windows machine).
The journal log is stored at either one of
/run/log/journal/machine-id/*.journal
/var/log/journal/machine-id/*.journal
Have you tried github.com/TengerTechnologies/Bricklayers yet?
I think this might improve watertightness considerably as in the tests it increased layer adhesion/strength by quite a lot.
open source, can be self hosted or you can use the official instance.