Don’t worry. This happens if you interrupt the reset process. Simply press Power to continue. The tablet will boot normally after 1-2 minutes.
This is the trickiest part. You need to press a combination of buttons simultaneously. I forgot my screen lock code for TECLAST T50
Before you forgot the code, did you enable Smart Lock? If so, your TECLAST T50 might unlock automatically in certain trusted situations. Don’t worry