Logitech K800 keyboard turns on and off continuously. help!

Hi, I have a Logitech K800 keyboard that I love and it's impossible to buy another one like it. Unfortunately I have to change it for only one reason: the backlight turns on and off continuously, even when the PC is turned off. So its battery lasts no more than 3 days. Do you think there is a way to fix it? I also tried replacing the battery, but the problem remained.Thanks for some advice.

Can you find a used one on ebay or similar? Not much you can do with keyboards but trash them and buy something else.

I thank you for your suggewstion. But I don't know a Keyword good or better than K800. Do you know one?

How about turning off the keyboard when not in use? Or at minimum decrease the brightness by going to Fn+ F5 Backlight down by 25% each click. According to the manual, 100% brightness will give you 15 hours of battery life.

You may want to consider an application (if you don't have one) like Logi Options+ where it appears you can set a time out for the brightness.