Mon May 31, 2021 7:18 pm
Bad things occasionally happen. Same thing has happend to me. Upon closer inspection, the board has some cold joint - if I poke a piece of empty PCB space by my finger, the board is willing to boot. If I withdraw my finger, it's frozen on power-up - the description of the OP is precise. You can try and take a look with a 'scope at the inner UART's TX output to verify (mind the empty resistor footprint, connected to the TX pad of the UART footprint. You need to probe the resistor's pad facing the CPU). If the board shows some hints of life, the UART will produce edges. When frozen as per problem description, in my case there are no edges.
I can think of several different possible causes to those symptoms - just think of all the balls on the underside of the CPU and RAM. If any of them develops a cold joint, you know the symptoms. Or if the Flash is dud so that even the bootloader fails to start...
You have just happend upon a rare error. Just RMA the product, *with this description*. I have RMA'ed mine and a replacement from my Mikrotik supplier is on the way. I don't think I have a reason to complain :-) This is the right opportunity to enjoy good RMA handling.