When you need to bypass a pattern, PIN, or password via a PC.

Look for firmware packages. Extract them to get the preloader. Trusted sources (use at your own risk, checksum verify):

This guide explains the importance of the Vivo Y20 (MTK) Preloader file

If you are a mobile repair technician or an advanced Android user, you have likely encountered the dreaded "dead boot" or "hard brick" scenario. For the Vivo Y20 (model codes: PD2034F, PD2034CF, PD2034), one of the most common issues is a corrupted Preloader partition.