Reaching a technique for doing the display rebuild took me
a couple of years but there is no secrets.
It's basically a matter of doing SMD work, contact-free soldering using hot air under a microscope.
The LED's are microtiny ½x1mm (0402) or about the size of this punctuation mark.
The LED's are normally only used in production and usually comes in production-rolls holding typically 2.000, 5.000 or 20.000 pieces.
For hot air soldering, I've tried different ways and brands.
I don't recall the brand I have at present but it was in the EUR 1400 range.
A vacuum holding tweezer device is used for handling the tiny SMD LED's
and soldering is done using solder paste (refrigerator storage!) from a dispenser running at pressurized air together with the vacuum tweezers.
The microscope is a fairly standard 20x/40x as you would use
for biological experiments in petridiscs but converted to lift
high enough to fit and focus on a display on a holding device underneath or, in some cases, a whole board.
Gloves, glue, tools and chemicals for clearing off the old junctions etc.
Furthermore, a Metcal soldering iron with a custom-made tip is used if a final touchup is needed.
Everything (including the workshop area) is antistatic to protect the electronics.
PM for info regarding belts.
Martin