If the file won't play at all, the "header" (the part that tells the computer how to read the video) might be damaged.

It has a built-in "Fix AVI/MP4" feature that can bypass minor index errors.

4K video requires significant processing power and specific hardware decoding.

A free tool that shows you exactly what codec and bitrate the file uses. If it shows "No video stream," the file is empty.

The "…" sequence often happens when text is misinterpreted as Windows-1251 .

Right-click and check "Properties." If it is 0KB or significantly smaller than expected, the transfer failed.

Try importing the file into Handbrake. If it can "see" the video, try encoding it to a standard 1080p MP4 to save the footage.