My bb-8 battery no longer charges. When placed in the charge cradle bb-8 simply flashes orange every few seconds. It is quite old now so I was wondering if there is a battery replacement or somehow a way to revive through replacing battery with subtle surgery.
Sorry to hear your battery is not working anymore.
There is unfortunately no way to replace the battery on that product. You can try to press the button on the cradle while the robot is plugged in a few time. Press it once to trigger the force recharge, then wait until the cradle light becomes solid blue. Press once again, and wait again. Repeat a few times (5 ish).
At some point, you should see the time it takes to charge the battery take a lot longer. There is a (small) chance that this can get the battery out of a fully discharged state.
I hope this works for you!