By chance I stumbled across this thread and found it very interesting. By accident I have been repairing the back panel PSU of Heatmiser neostat V1’s now for several months.
The background for this is that I built a large Scandia Hus property in 2011 with UFH on three floors. I fitted 24 x 12v networked Heatmiser PRTN style touch thermostats, touch pad and a net monitor to connect to the internet. This actually worked quite well until recently where the Heatmiser app is now just about useless on the iPhone latest IOS. So I looked at changing over to neostats with a neohub but there is no direct replacement for all the thermostat types that I have. In addition, the neostats look like a backward step in both aesthetics and function to the touch screen stats.
I purchased a neohub and some cheap faulty neostats from eBay (which I repaired) to investigate the Neo app and whether I could fake my existing system with HW/SW to operate with it. Unfortunately this turned out to be near impossible due to encryption of data packets using SSL and Heatmiser would not help me.
However, from my experience with the neostats, I do have a clear understanding of the PSU design and why it fails. I have repaired quite a few now but use much higher spec parts than the parts that Heatmiser have assembled them with. The repaired PSU should last a lot longer than the original. If anyone wants their backplate repaired then I may be able to offer that service at a small cost if that sort of thing is allowed on this forum.
I am now investigating a HW/SW solution to allow my legacy netmon based system to be used under Apple HomeKit via a home hub and hope to make good progress with that very soon.