Tab ejects usb while watching vids and screen flickers then turns off

[Alexander Supertramp]

While watching movies on a usb stick, connected to my Samsung Galaxy Tab4 via a cable connected to the charging port, a message comes up saying "Cannot play this video". Then the usb is ejected automatically, the screen flickers for a while and turns itself off. (This can happen after a variety of periods watching videos and at a variety of battery levels). It cannot be turned on again without putting it on charge. Once on again I have tried to plug in the usb cable and stick but the tab will not recognise it.

Can anyone help?

Jerome