This is the topic i was looking for.
I have two pieces, one that is still older version and working (v4.2.3).
The other one is my vpn that i use on occasion, that has suddenly failed and was in 4.6.2. I'm willing to ship this one piece wherever so you can examine it?

Unless there is an easy unbrick solution by now, because i'm not familiar with UART.
The snapshot on openwrt will not help me either without luci. I tried downgrading to 4.2.3 as well but that didn't help...