My 4 year old Polaroid CRT TV/VCR/DVD combo (model TBX2000-AF) will not display a picture. When the "power" button is pressed the TV will make the clicking sound of relay indicating it is on. However, there is no sound or picture. Any suggestions or diagnosis would be great! Thanks.

 

That kind of thing is usually a self-protection type issue.
When a set is powering up, a controller checks the various power supply voltages to make sure that they "come up" in the correct sequence and are within certain tolerances. If that doesn't happen, it shuts itself down, and you have to unplug the thing for a minute or so to re-set the controller.

This is a safety feature. TV sets from many years ago didn't have such protection circuits, and would emit X-ray radiation.

Televisions with CRTs (cathode ray tubes) have very high (and lethal) voltage levels inside the case; 18,000V or more is typical. This high voltage can remain even if the set hasn't been turned on for weeks or more.

My best advice is to take it to a TV repair shop. The fault could be as simple as a burned-out Zener diode. However, it is not worth risking your life to attempt to repair it, particularly if you are a neophyte to electronics.