What is wrong with it ?

Your disc must have the same region code with your player's region code, or you won't be able to play it. However you can always play region locked disc on PC with region free player software, or you can rip it to MP4 and play it.
Best Blu ray DVD Region Free Software How to Rip and Convert Blu ray to MP4 with Blu ray to MP4 Converter

What you mean?

You may get the wrong format for your MP4 Player.
So i recommend you to use a video converter to convert the videos you have to the one you need.
i have used this video converter for long and it is really easy to handle.
Go and have a look.
http://www.leawo.com/leawo-video-converter/

Whether the li-ion battery has no energy？ Try to charge it. Also the fireware of mp4 player is wrong. If it is, you'd better contact the seller or put it to repair.

Turn on the MP4 player and let the battery go all the way dead. Plug it back into a computer and mine reset.

use smart movie convertor first convert ur videos to the compatiable format then download in to ur Mp4 player

mybe you have it on auto play

You'll need to open up your player to find the plate and board ID numbers to be able to find a compatible firmware for your player. Take a look at this post here: http://mympx.org/forum/knowledge-base-faq/41330-how-recover-dead-mp3-mp4-player.html. This will tell you how to recover your dead player using your firmware.

Hope that helps.

complain to the maker.

BURN IT naaa thers nothing you can do you probably formated it wrong and deleted the thing it boots from eg firmware

soz unless it has an reset swich i sujest start looking for a new one
i sujest this site i brought mine from here cheap as and cool desins
(www.uxcell.com)

bass-master