According to your description, Samsung S3 mobile phone does not support signature unlocking. If you plan to change the phone screen lock password, I suggest you:

Open the phone settings-lock screen-lock screen-lock screen-select "None" to try. After the screen times out, the screen of the mobile phone will automatically dim. Click the power button or the Home button to directly enter the application.

If not, please send the machine to Samsung service center, and the after-sales engineer will help you unlock it safely. Please visit:

Samsung knows to provide you with high-quality solutions and answer your questions attentively, hoping to get your satisfactory evaluation.