You invert the display by peeling off the top polarizing filter, and installing that new one rotated 90 degrees relative to the how the original one was installed. You have to buy a new 180 degree polarizing filter for LCDs, ebay or amazon has them.
Just like this:
https://hackaday.com/2014/04/24/simp...watch-display/
For the LEDs, I simply desoldered the original ones on the face plate PCB, and installed new ones that I bought from digikey. I do not recall the part numbers. I just looked for 0603 surface mount 605nm color LEDs for the buttons, and two 5mm 605nm color LEDs for the display.
I picked the brightest LEDs at 5mA test current for the 0603 sized LEDs, and the brightest LEDs at 20mA test current for the 3mm LEDs. Digikey.com lets you search by color, size and brightness pretty easily.
You have some small margin to adjust the brightness too. All of the LEDs have a series bias resistor, which you can adjust up or down in value by +/-20% or so if needed. To find which resistor controls which LED, just follow the traces on the PCB.
If you don't have surface mount soldering experience, I do not recommend changing the button LEDs. They're quite difficult to replace because the traces are very large, and the 0603 LEDs are quite small, with very small pads.
If you're really not feeling confident you can PM me, I might consider some sort of service.
Edit:
Here is what I actually used for LEDs.
Display:
https://www.digikey.com/product-deta...262-ND/4901619
Buttons:
https://www.digikey.com/product-deta...3-1-ND/2356228