I been working for a network infrastructure company doing planning and estimating for about ten years. I've been interested in switching industries for sometime since I have always been much more interested in coding than the infrastructure side of networking. I have recently gotten my PMP and I have a BS in CIM.
Is getting the PSM 1 a good move? There would defiantly be learning curve to pick up the software industry, but honestly, there is a learning curve involved in any industry switch.
I've taken the open assessment a few times and I'm scoring 90% on it. I've read the guide and I've read the book "Essentials of Scrum" about a year ago.
I'd suggest you get involved in some open source projects to obtain coding experience. Most OS projects need documentation done and that can be a good low-risk starting point.
There's arguably a more limited opportunity to grow agile development skills by going that route. However open source contributions can look good on a resume, especially if they are for software development tools that potential employers use themselves.