Wandboard Quad refusing connections

[Lestrad]

Hello to all. I recently installed Arch on my Wandboard Quand following these (excellent) instructions:
https://archlinuxarm.org/platforms/armv7/freescale/wandboard

Everything was working well once I solved the Samba problem (see my recent post), but suddenly the Wandboard is refusing all connections. It does respond to pings with no problem. The only thing I've done recently is to change my locale from the default "C" to a UTF8 locale setting.

The problem is that the only way I have to make any changes to the system is to SSH into the Wandboard from my desktop PC, but the connection is refused. Otherwise all I can do is remove the SD card the system is on and open it from the PC under Linux.

I know that I'm supposed to be able to connect to the Wandboard via its serial port, and I'm in the process of finding a null modem cable so that I can try that. But in the meantime any suggestions would be most welcome.

TIA
Les