I estimate that your battery is a maintenance-free lead acid battery. 25 months is enough.

Want to repair, one is whether there are materials and maintenance tools. You also need some skills. Repairing the battery was in the 1980s. At that time, electricity was unstable, so people used it on black and white TV. Few people use it now. So you can't fix it if you want.

Therefore, it is better to buy a new one. In addition, the battery can be used as long as 12V. The bigger the VA, the bigger the volume and the longer the time. Choose for yourself.

I wonder if there is any distilled water in your battery. You can open it. If it is dry, try charging it with some steamed water. Don't give up any hope. Such a well-maintained battery can last about 2 years.