GM key fobs are considered "non-servicable" they do not provide the individual components for the fobs (save for the battery). A whole new fob may be needed to correct the problem, which you did not include in your question. If you need a battery they can be obtained many places that sell smaller batteries, walmart and the like.

The 2 CR2016 3 volt lithium batteries are the the only serviceable parts, I found them for $25 at iKeyless below:

https://ikeyless.com/vehicles/Oldsmobile...

eBay is the source for these.