If you cannot find the file, email the manufacturer’s support with your request:
Item description report * TP SK508S PC821 compatible: Works seamlessly with TP SK508S and PC821 models. * Easy installation: Plug- AliExpress Tp.sk518d.pc821 Software Download
You can find the official stock firmware (Flash File) and relevant drivers on several firmware repository sites: If you cannot find the file, email the