Here's an excerpt from the Sony Manual online. And the link - http://esupport.sony.com/US/perl/webtree.pl?template=EN&mdl=KDF55XS955&content_id=68&category_id=11&problem_id=52
The POWER/STANDBY (red) indicator flashes three times
If your power/standby indicator is flashing in a pattern of three flashes, this may indicates that the lamp cover is not attached securely. Follow the directions in the Operating Manual under changing your lamp that related to closing and securing the Lamp Cover. Ensure that the Lamp Cover Door is securely fastened by tightening each screw. The POWER/STANDBY (red) indicator flashes continously
If your power/standby indicator is flashing continuously, and the lamp cover has been secured, your TV may be in need of service. The POWER/STANDBY indicator is lit up green (not flashing)
A sustained green light indicates your TV is on. The POWER/STANDBY indicator is lit up red (not flashing)
A sustained red light from your power/standby indicator simply indicates that your TV is in standby mode. This shows you that your TV is ready to be turned on with the remote.
Is it the power light and not the lamp light? If the lamp light is flashing then replace the lamp.