I bought my S50 in December 2023 so I had it for one year and a half now and I do remember how frustrating using the S50 the first few times was, do not worry, once you manage to do it a few times it gets much better.
The troubles locating the Sun and the Moon are well known, nothing new here, I would not worry about that. For night time you should not try the moon or the planets first, the 3-point calibration, both in Alt/Az mode and in EQ mode is designed to work on stars.
Compass calibration is important but you do not have to do it every day, in fact, I do not remember when I did it last and I am using my S50 every clear night I get. In Alt/Az mode (this is from memory, I have not used this mode at all since EQ mode has been released a few months ago), you have to chose a relatively bright star, between 40 and 70 degree altitude, with enough clear sky (about 30 degrees or so) to its left and right. You select it as a target in SkyAtlas and the rest should happen automatically. If you have an EQ wedge (if nothing else, one could be 3D printed) I strongly recommend it over Alt/Az mode. The calibration is a bit trickier but not by much, you need a clear zenith view (although there are workarounds if you image from a balcony), you start with the S50 axis pointing as close to North as possible and then do EQ mode calibration, following the instructions of the app.
It is unlikely you have a bad unit, keep trying and once you succeed a couple of times it will seem easy.
