Red Dot - 0023 Light Code

Got this a while ago, not sure what it was, was working before i stopped using it, for about 5ish years, now it has a red dot, doing the trick to see the code, i get 0023. Any ideas on how to fix, or what to buy to fix?
Want to stay cheap since I have my original, if this one can get working i can use a few of my games again.