Hey, i am really sorry about your faulty machine, that suxx. I guess there is not much you can do, disassemble and check which linear module is faulty.- After that i would look into the module to find the issue, maybe its mechanical.
Alternatively:
https://support.snapmaker.com/hc/en-us/articles/360051985253-What-should-I-do-if-some-linear-modules-stop-working-randomly-