[Elecraft] KPA500 fan won't shut off

[jerry]

After yesterdays contest, I noticed this morning that the KPA500 fan was 
still running at a high speed even though the amp had been turned off 
all night by using the front "on" button.  The only way the fan stops 
running is if I turn the amp on with the front switch or if I shut the 
amp off by using the rear on/off switch. Menu setting for Fan is set to 
normal. Any ideas?