You don't need to re-sign, you can log on to the website every half day and try another mobile phone.
If all the above are unsuccessful, you need to send an email to China Teacher Qualification Network, and the email address is at the bottom of official website's homepage. Explain the problem in the email and attach your account password and ID photo (to prove that you are yourself). China Teacher Qualification Network will test the question after receiving the email, and then give you feedback. You still have to do the final signature yourself.