If anyone is still interested, the problem is IC100, the square chip that drives the display.
I had the same exact problem described in first post.
I fixed this.
Removed the board.
Took a heat gun to carefully remelt the solder holding chip to the display board.
Also, it is a lot of heat. Should try to protect board traces. I slightly bubbled them on one side.
But it is working.
In future, some kind of shield foil wet paper towel etc... good idea!
Using a solder pencil, I resoldered IC101 and the fluorescent display connections.
I saw NO visible problems with IC100.
Ever hear of tin whiskers? might be.
If tin whiskers would a brush work, or could you use an acid to dissolve whiskers around that chip?
chip is this
UPD16315GB-3BS Manu:NEC Encapsulation:QFP,1/4- to 1/12-DUTY FIPVFD
**broken link removed**