My s1 vertebrae is not fused. I've had 2 nerve blocks and no relief. What should I do next?

Re-operate? When a fusion surgery fails, you need to carefully reevaluate the potential causes. Then, with persistent pain, re-operation is often indicated. This has to be done very very carefully and often with a different approach to make sure it fuses correctly. This is a complex problem and is worth a second opinion or evaluation at a tertiary referral center.
Get another opinion. As that is not a diagnosis I have ever heard of and therefore i doubt these injections would be doing anything in the first place.