I have the same problem with a whole batch of CRS317-1G-16S+ switches.
I managed to upgrade two of them successfully by installing 6.41.1 and upgrading the RouterBOOT firmware to 6.41.1. The routers shipped with 6.40.5. My mistake was to upgrade the others directly to 6.41.2 and skipping 6.41.1 and not upgrading the RouterBOOT firmware. They are now all bricked. I can still boot into SwOS though, but that's not what I want.
Below is output of switch that succesfully upgraded, as you can see the RouterBOOT firmware is at level 6.41.1
routerboard: yes
model: CRS317-1G-16S+
serial-number: 7A1408B55E44
firmware-type: dx3230L
factory-firmware: 3.43.2
current-firmware: 6.41.1
upgrade-firmware: 6.41.2
In summary: Upgrading directly from 6.40.5 to 6.41.2 results in bricked switches with exactly the same symptoms as others here described. It seems like the shipped RouterBOOT 3.43.2 is incapable of booting 6.41.2 or later (have tried even the RC candidates).
Downgrading to 6.40.5 via Netinstall also results in the same problem, kernel never loads and "Starting..." never appears. I can successfully run netinstall and install any of the later releases, but the kernel also never loads And now I can't even downgrade to the orignally shipped RouterOS.
So it seems like there is a RouterBOOT problem, perhaps a flash variable that gets changed or something that stops the kernel from booting post upgrade.
Mikrotik, if you could make available the dx3230L_x.xx.fw firmware file for RouterBOOT 6.41.1 I will try to upgrade the RouterBOOT to see if it resolves the problem.
Normis, would be great if you could step in here.