[Elecraft] K2 frozen at start up

[Silvio IZ5DIY]

Hi I'm Silvio IZ5DIY,

while I was running a qrp long-wire setup by a little tuner, I touched
my K2 and experienced a "electrostatic" discharge.
A storm was coming and a lot of static energy was on air. I had cut -
yes had to cut - external wire antenna, I was unable to remove antenna
connector from K2 without discharge, or to handle the wire outdoor at
the tuner connection.

After first discharge experience I switch off K2, but not disconnect...
I was to much "spark".
Later my cut and try to bring to ground all antenna, next I remove all
connection to K2 (no more discharge).

I tried to power on again and after Elecraft message the frequency was
frozen. No more control or buttons working, only power know was working.
I was running qrp on RTTY mode, and it is still locked in this way.

I looked at this mailing list archive to see similar experience and I
found something.
http://elecraft.365791.n2.nabble.com/K2-freeze-at-startup-need-advice-td1099894.html#a1100892
http://elecraft.365791.n2.nabble.com/K2-CONTROL-PANNEL-FREEZE-UP-K7CJA-td3749758.html#a3749758

They lead me to a "fixed tx" behavior.

Based on second link thread I check my control board focusing on U6.

First I check U6 pin 30 level and it was low: 0,12v. Checked for any
problem following DOT-PTT line (  CB - RF - Front): no problem.
I check R value at RP4 5-6 and it was around 3K, not 82K as required.

I measured level at U6:
pin 25 TXD close to 5v (4,94)
pin 26 RXD close to 5v
pin 27 TX 0v
pin 28 RX 0v
pin 29 /DASH close to 5v
pin 30 /DOT-PTT  low 0,12v

I measure Q1-Q2 collector: both close to 0v.
I think if it is really "stuck on tx" I should find 8T (collector of Q1)
at 8v level... but it is low.
Measure at Q3-Q4 gate: both to 0v.

Next test I made: removing U6 from it socket. I check again resistance
at RP4 5-6 and found correct 82K.
I check resistance value at different pins at U6 (alone U6) referred to
pin 31 VDD
U6 pin 29 - 31: high impedance
U6 pin 30 - 31: 2,7K

My think is U6 is gone. But it's strange it is stuck on TX without 8T level.

Any guy can confirm my idea? Any more check?

73, Silvio IZ5DIY