Try placing a marble, or steel bearing inside it to help mix it while shaking. Do not micro it. This was brought up a long time ago, and it was strongly discouraged. If it is hot where you are at, place it in the heat for a while. Maybe in your car in the afternoon, then shake it. It may take a while.
If it will not mix, then you may need to use another bottle of T-Gel and mix them together so your product isn't wasted.