The courses at General Assembly look pretty good. Does anyone have experience of these or are there alternatives out there?
https://generalassemb.ly/education/digital-marketing
I made the transition from a technical analyst background this way. Back in the day I was fairly handy with Excel/Access/VBA type work. I was working in a large company and hit up some marketers and asked if I could build tools/reports to monitor and improve ad spend in my spare time. This helped them optimise a bunch and they got a new headcount and gave me a permanent role. If you have a similar option it would be easier than trying to convince a new company to take a chance on you.
Also what do you mean by technical marketing role? This could mean a bunch of things. If doing courses or practical experience you should decide what marketing field you want to go into to focus on. People from ouside the profession don't typically realise the level of diversity in skills/role. If your not sure let me know what your trying to get out of this move and I'll try and offer some advice.
Here's an idea. Pick a product on Clickbank, set up an affiliate and train your marketing chops with it.