Coby rc 057...when I turn the volume up the volume keeps turning back down all by itself. How can I fix this?

Coby Programming

https://www.google.com/search?q=coby+rc-057+remote+programming

Proscan Codes

https://www.directutor.com/content/remote-control-codes-proscan-tvs

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0018, 0011, 0000. Try these codes. If you wish to get more details; check the sites linked here. It has set-up code list & set-up procedure to many popular brand remote controls. Common set-up codes to check with TVs and other devices are given, in the order of the "device's brand name list" in alphabetical order. Pull up older posts.
http://electronicshelponline.blogspot.com/
http://electro-medical.blogspot.com/
http://remotesearch.blogspot.com/
http://electrohelponline.blogspot.com/
Search the site by type in the brand name to your device, in the "Search box at the top right of the display window" to see the set-up codes to your device, with different brand remote controls.

look for system reset,

0045.0041. Try these codes. If you wish to get more details; check the sites linked here. It has set-up code list & set-up procedure to many popular brand remote controls. Common codes used for devices too are given, in the order of device brand name list in alphabetical order. Do a search by type in the brand name of your device at its search box, and press "Enter".
http://remotesearch.blogspot.com/
http://electrohelponline.blogspot.com/

could be many things, make sure nothing is around the tv that would block the receiving eye for the remote on the tv. sometimes the receiver in the set can go bad.

Contact ARRIS for Consumers .

Mark
Motorola Support

Refer its user manual for details. If you wish to get set-up codes and other details check: http://electrohelponline.blogspot.com/ & http://electro-medical.blogspot.com/ Both the sites have setup code list, and setup procedure to many popular brand remote controls. Check the site in 'Mosaic' view. It will make search easy.

test the main switch for faulty, and replace it .
God bless you

I sucessfully programed the AUX button on my Cable remote to my Coby DVD player (model DVD-227) using code 21107. You can also try these codes: 20778, 21086, 21351.

I hope that helps!