I have RB2011UiAS-2HnD running 6.13 which has been working fine for many months.
However recently it's crashed (twice).

The symptoms are that it's seemingly completely dead, it isn't routing, doesn't respond to pings and I can't access it via SSH or the web interface. Also the touch-screen is blank and non-responsive.

On both occasions I've had to remove/re-apply the power and it's come back up fine.

What I'd like to know is what's the best way to fault find this. For example are there any specific logs that I should capture to look at if this happens again.

Thanks in advance.

i got the same problem with my RB2011UiAS-2HnD, just happen days after the warranty ends. Follow the netinstall procedure to reinstall RouterOS (latest), router will run for a couple of days then will start to have same problem, will hang most of the times with no reason. Now it's totally unusable. Maybe try to do the netinstall first and hopefully it will be the solution for you..

I've configured the watchdog functionality so hopefully if (when) it happens again it will at least restart on its own.