Hello.
If you replaced the lamp and now it doesn't power on at all, I suggest you verify all the doors you removed to change the lamp. If one door/plate is incorrectly closed, there is a switch which will prevent you from starting the TV.
Also, have you unplugged the TV for more than 1 minute since changing the lamp? If the TV was plugged when changing it, you will need to reset the TV by unplugging it for 1 min or more.