Ok, i assume (writing this) you're able and skilled enough to work on the inside of the tv.
Try starting it up with the (video output-) board removed from the tube.
If, when swithed on, it makes the crackling sound of the EHT coming up, it's another sign the tube is (probably) finito :(.
I'm not sure if this works for a BV3 but it does with avant RF, just switch it off again a few seconds after doing this, not sure if it would cause any more damage keeping it on (but knowing the avant, not very likely...).