If the power light is continuous it means that it isn't able to achieve the target temperature. I would be careful about turning it up more. If ambient conditions allow it to achieve target, it will overheat.
Can you build some barriers around the incubator to keep it from losing heat? Basically creating a mini warm room. Perhaps build a wall with cardboard a few inches from each side. Cut some cardboard and cover the windows. Whatever you do, don't cover any holes since they need air, especially now.
If you do that, you may find you have to turn it down. Once the power light cycles, that's when it has achieved target temperature based on the dial setting.