I filled in the student union registration form, but I didn't send a text message to remind me of the written test. What happened? Was it eliminated?

Generally, people will not be eliminated directly just by filling out the application form, at least after a written test or interview. Either you dropped your application form, so there is no information for you there; Either your phone number is wrong, or your handwriting is unclear, which makes it impossible to contact you. You can ask the student union.