Replacing the kindle 4 screen really isn't as difficult as it may seem, Tedious? definitely, but not impossible, I bought a broken screen kindle 4 off ebay and was determined to fix it up, before removing the back cover, I used a blow dryer on high heat and waved it over the back cover for some time, this loosened the glue enough for me to remove it without destroying the battery. When you get to the actual screen, again use the heat gun to loosen the glue behind the screen once again, It still ended up breaking off in chunks but it was large chunks instead teeny little pieces, once its off, I started off with goo gone and a paint scraper to get the big glue chunks off, afterwards, I used a dremel with a very light sanding head (Highest grit you can get) and sanded off the rest of the glue, I didn't reglue the screen, I simply put the new one in and it fit perfectly and works like brand new
Dont listen to the naysayers, it can be done! admittedly during the process I too thought I bit off more than I could chew but I stuck to it and glad I did it, it will take some work and perseverance, but in my opinion, absolutely worth it!