Did you already try the steps here for further isolation? If that didn’t help, PM me the serial number so I can validate its model and check for other model-specific workarounds to help you address the issue. Thank you!

Hey bud so did anything help out? I’m having the same issue and its only been 9-11 months and I dont use it heavily. 

did anything help ? i have tried everything, nothing seems to work

Hey fellow nerds, I may have your fix. 
Surprisingly simple, I know, but I just had the same issue and lost my mind.

Before doing this, I tried: 

• Uninstalling and reinstalling both Synapse and Cortex
• Turning off and on the mouse
• Keyboard duster under the two buttons
• Repair tool for Synapse

What ended up working was plugging it into the device that I was using. 

This instantly fixed it for me. 

Hopefully this is your fix! Best of luck peeps!

What does this mean?

this happened to me too, but only thing that fixed it was just hitting the mouse against my hand fairly hard.

I had lost the use of the forward button on the side of the mouse, and the DPI up button on the top, but hitting the mouse allows it to work for a while before it stops again, until it’s hit. 

Like some ancient device. It doesn’t seem to be a software issue. Plugging it in does not make any difference, and I’ve uninstalled and re-installed Synapse multiple times.

the only thing that worked, thanks

im having the same problem, but with the up sensitivity button and the scroll wheel. I tried updating synapse and the mouse, using it wired, just about everything, but its still not working. ive been having this problem for about a year now and ive just learned to live with it by reassigning the actions to different buttons. For example, since my up sensitivity doesnt work, i reassigned my down sens button to cycle through sensitivity stages rather than just go down. Razer Hypershift also helps. I use Hypershift to scroll by assigning my scroll wheel button to Hypershift and my side buttons as scrolling up and down. Hope this helps

Slapping my mouse in the palm of my hand worked for me… Looks like I need to get a new mouse

I am posting now in July of 2024 just to comment that this unironically worked. I’ve had this issue before and also tried reinstalling and updating everything I could think of. Yet a good ol’ smack into the palm of my hand and it’s working good as new. Appreciate you bro.

I had to log in to say the same thing. My sensitivity down button stopped working out of the blue (to be fair, I've had this mouse for years by this point) and while searching for answers I came by this thread. And my guy, slapping it against my palm returned the button's functionality. Thanks for the help.

this surprisingly worked 

Just want to come here and say, and also so that this helps this post stay at the top of Google, had the same issue with mine and unbelievably slapping the mouse in palm of my hand fixed it instantly. I really can’t believe it… certainly must be some common hardware issue with the Deathadder.

open the mouse, reconnect the connector ( most probably got disconnected ) as it has no lock in mechanism.

To open the mouse:

1- Remove all 3 white pieces at the bottom

2- Unscrew the 4 screws accordingly.

3- slowly pry the mouse open from the side first.

4- connect the cable that goes from the top part back in its place

5- put the mouse back together.

Please note, once the white parts are removed, it will be difficult to attached again, or cause a slight inconvenience while using.

This is my own trying and this is what i had to do to make the buttons work again.

it is not my comment someone else write this but when i open my mouse the cable was disconnected as soon as i plug it back the return to work as useual and it fixed my problem.

good luck and dont be afraid to open up the mouse it is very easy only 4 screws.