This article was originally published: November 4 2013
It may therefore be that some links do not work anymore.
How to use Baofeng UV-B5 flash-light switch for LCD background light.
On the blog of Peđa Supurović are instructions for the disassembling of the Baofeng UV-B5 radio and also how to modify it to enable the third (Flash light) button to switch the LCD and keyboard back-light on/off.
If you are interested then go to this website: Baofeng UV-B5 flash light switch for LCD back-light