HUD display works sometimes

[analogkid455]

When I first got the car, the HUD worked most of the time but would fade out some times. I took it out to resolder the light sensor or whatever it is that causes this usually.
Then, it worked less than it did before. Now it comes on once every couple of months for about a minute. What is my next step?
Another thing is the clock on the radio only displays when the car is cold. Then it slowly fades off. I already replaced the lights in the display.