I had a similar thing happen today, something with the case was either putting pressure on the analog board or something else that needs repair and the CRT wouldnt power up, but as soon as I removed the back case, it powered on properly.  After a few times taking the back off and carefully putting it back on, I got it together just right and now it works good.  But obviously needs an analog/mobo recap. You should take the case off and power it on that way, see what happens.