@Joseph-TP I don't think I asked about your warranty policy. I asked the community to specifications around the otherwise very clever idea of a separate recovery system. It is odd I was able to restore another identical device this way, but not this. Same device, same software, same procedure.  
Anyway, instead of being so worried about your warranty obligations you should perhaps consider how many are buying your devices because they can be modified with alternative software. Ever thought about that?

Now the interesting twist is - I was able to restore the OpenWRT "factory image" through the ax23's recovery subsystem, but doing the same with any of the tp-link official images bricks the device.   Like I already explained, there is a quick flash of some red text, but it goes to fast to read. Would be nice with some better software development and testing so at least it's possible to understand what goes wrong.  I have been able to debrick another ax23, an Archer C6 and Archer C7, so I'm sure I will succeed eventually.  

Again, if tp-link would opensource their proprietary port drivers I'm sure OpenWRT would performa as well as the proprietary software. As it is, the only shortcoming of OpenWRT is that due to lack of hardware support of the tp-link ports, the ax23 maxes out at around 400 mbps with openwrt, and only the proprietary drivers allow for the full gigabit throughput.