An update. I have tried using Araldite Epoxy Mixed. Failed to fix at the first time, then managed to "fixed" it. Not perfect, but still can transform between fighter mode to Gerwalk mode with a lot of extra care. The hinges are missed align and I have to trim to make it work. There are more and more breaking parts. For instance, super strike parts cracked when it's removed, a crack behind the feet, the gun pod holding the belt chain cracked too.
VID-20201221-WA0044.mp4