The hot air escaping from the chamber :
. . O A I R T M X N
E H T J B R M L H D
B A U F K P V P O P
Q L G J Q S N R W S
O S I O S R C K Y X
W Z R J J J U C G A
V G N E Z n X N V S
R M Y D P J U G C I
Z W R J B B I F I U
G S A T C K B Y R .
OTP decrypt with ABC