Okay, well the news is not good from KSC this morning. The media briefing is off until 2 pm this afternoon but the launch of Endeavour is definitely off for a few days at the very least.
Rather than just change a thermostat it looks as though they need to change the whole electrical box of tricks - which has to be followed by 48 hours of testing.
There is a chance the launch could switch to Thursday or Friday if the negotiations depending on how the Atlas launch is progressing and whether that could be changed. Otherwise it is most likely to go until early next week. A new launch date will be set tomorrow.