Well, this seems to be rather common now.  My one R4 B2 that's been running for 4 weeks had one board stop working yesterday.  After reading here that it's been happening to others and that some have gotten it working again by updating the firmware, I tried that also.  Firmware update seemed to go fine, but only 1 board working still and after the firmware update the other board seems to be working but it's showing a large number of total HW errors even though the working board errors are almost none.  Now what?