Update arduino fio bootloader to support Watchdog

I want that my arduino fio supports watchdog to be able to use it on my project.

I tried examples given by Nick Gammon in this post: Watchdog in Arduino Library - or at least support by bootloader - Project Guidance - Arduino Forum

But it starts to get reset constantly and I have to power off and on again to be able to reprogramming it.

I haven't found a bootloader for arduino fio in arduino's webpage.