[Elecraft] K3S stuck on MCU LD

[Don Pomplun]

A few days ago I noticed that when I powered up my K3S (ser #11141) I 
would briefly get an Err DSE message.  The manual says I should reload 
the firmware via the K3 Utility program (like I've successfully done in 
the past when a new version is available). But this time when I click 
Send All Firmware to K3, I get this:

Elecraft K3 Utility Revision 1.16.7.25
OS Version 6.1 Build 7601 Windows 7
K3 MCU revision ??.??. RS-232 speed 38400 bit/s.
Sending firmware file C:\Users\K2BIO\AppData\Roaming\Elecraft\K3 
Firmware\hmcu0567.hex to MCU
/(5-10 second pause, then)/
Error code 0xE2000048: No response to poll while synchronizing to buffer 
boundary
MCU verification failed. Reload MCU.
Click "Close" to close this window

I disconnected the Power Pole connector for a few minutes, then powered 
it up again.  After the front panel LEDs flash briefly, the screen says 
MCU LD and the red TX light is flashing. Trying this again many times, I 
get the same message.
Then I noticed that with _no power to the K3S and the USB cable between 
the K3S and the PC unplugged_ at both ends, when I start the K3 Utility, 
and click /Send All Firmware to K3/, I get exactly the same error 
message as noted earlier (with nothing connected).  Thinking maybe the 
problem is with the K3 Utility, I deleted it from the PC and reloaded it 
from the Elecraft site and reinstalled it.  Same problem!
It appears that even after a long power-down, the K3 processor isn't 
resetting.  Looking for suggestions!
TIA
Don    K2BIO