[Elecraft] Remote firmware upgrade failure

[M Cresap]

After several months of successful operation with MCU firmware 3.97, 
I attempted to remotely upgrade the firmware from 3.97 to 4.22 using 
the latest K3 utility (ver 1.3.11.5). 
It failed. The K3 utility had detected a 38400 baud rate, even though 
the radio had been set to 19200 baud. The utility could not continue, 
but it did manage to disable the remote RS-232 input in the process. 
Now the K3 Utility autobaud routine sends hex 3B (semicolon) and 
in return usually receives hex 7B (left bracket). Occasionally it will
receive a longer string - something like 7B FF FA 2C 6A 04 FF F0. Once, 
while testing for 9600 baud, the K3 utility sent hex 54 42 3B (TB;) which 
doesn't make sense.
I have tried cycling power to the K3, then holding the power on pin 
(pin 8) of the ACC connector low for 10 seconds as the owners manual 
sort of suggests (Manual Rev D5, page 45). (I can't hold down the local
power button - it is many miles away!)
I've tried using Hyperterminal to send semicolons. It consistantly returns the 
left 

bracket symbol, no matter what speed I set Hyperterminal to. 
Sending enter (hex 0D) returns hex 7D.
Anyone have any ideas how to remotely recover the K3's normal operation?
73,
Mike W3IP