Shibby build v123 + WNR3500L v2 = "Error erasing MTD block"

I just tried upgrading from Shibby AIO build 101 to 123 on a WNR3500L v2 and got an "Error erasing MTD block" message. Has anyone else succeeded in installing the 123 build?

I wonder if the router had a hardware problem or if it's a problem with the firmware.