After several years of good service, my strimmer packed up, so I bought a new one. Firstly the supplied written instructions needed a degree or PhD in astrophysics to follow. I gave up and looked on YouTube for an instruction video from the manufacturer.
I watched many many times. These were better, but not by much. The last stage was adding the steadying handle. What the video failed to explain was that you had to pull something at the same time!
In all, I was not at all impressed. My last strimmer came assembled and just worked.
If it goes wrong, I have no idea how to disassemble it to return under guarantee as most assembly steps assumed you waited for a click. Perhaps you need a PhD in theoretical physics for that!
I assume this too was made in China by slave labour and is designed to fail just after the guarantee expires.