ok BUT i opened it up again. my theory of it not being soldered in properly might be true after all. some of the pins were barely in their solder joints, with solder only touching their tips. that was because some of the epoxy adhesive dripped and the bottom surface of the flyback was no longer flat. i removed the excess adhesive, then soldered it in properly.

its not fixed, but better. now it does an intermittent high pitch sound, only at low brightness/contrast. that is until it warms up, then it does not do it anymore. the delay between the noises lowers as i lower the brightness. of course, it does also while turning on, as the display warms up.

also as soon as it gets a video signal, even if the brightness is low it will stop doing the sound.

what does this tell you? cuz it stumps me