To confirm, you are going to root, then /media/sdcard/ ? Have you tried another Micro SD Card?
It may be the storage is faulty. Are you 100% sure it is a T8-S Plus v1? Check the label on the bottom of the device, it should say...
I have removed the original v2 firmware link from the first post. Thanks.
We will make a tutorial for it once we start shipping the next batch early/mid next week.
I have updated the link to the GitHub page for the latest version.
Separate names with a comma.