First of all you need to warm up the material either in the middle of the indentation and the edges. You need to be careful to do not melt the plastic, but just warm it up until you cannot touch it. You should not spend more than 10 min in this process.
Now you need to push back the nose and make it back to the normal shape. To do that, you can push with a rounded shaft from inside. You might need to remove the footrest to better work in that area.
This process depend upon your type of damage and you need to use your imaginativeness to solve your issue. You can for example use your feet to pres in the right place. If the material cool down to much, you need to warm it up again.
To finish your job you can warm everything up again and melt a little bit in the stressed points without touching it. In this way you'll reconstruct the material strengthens.