Having the same problem with my PT-AE700E.
Projector powers up fine (screen image looks great, fan can be heard) then powers down in 3-5 seconds with both LAMP and STANDBY LEDs on RED.
At this point, pressing the power button does nothing. The ON/OFF switch at the back needs to be switched to OFF and back to ON to allow for above process to be repeated.
Replaced the lamp and no difference.
Been thinking that the LAMP timer needs to be reset but I don't have enough time to enter the menu to reset it, thought there may be some other way to do it.
Then after searching and searching online without coming across this issue much at all, thinking it's not even the lamp.
The TEMP LED does not illuminate, ever.
Hoping someone has an idea what's wrong with this thing.