Converting MP4 from usb flash drive

I have a new Sylvania SDVD1332 portable DVD player that wont play my MP4 videos from my flash drive. When I switch the DVD play to USB it reads CODEC issue unsupported on the screen, but it accepts my JPEG pictures and files. How do I use CODEC to convert the MP4 videos on my flash drive to play in this Sylvania DVD player?

Your MP4 files probably contain H.264 video, which is not supported by that DVD player. You need to convert it to MPEG-4 video.

Here is a free video converter:
https://handbrake.fr/

As container format select: MP4
As video codec select: MPEG-4
As audio codec select MP3