Before proceeding, readers really need to check the comments, and also get a 2nd opinion - such as from YouTube videos of other users, and the actualy article created by iFixit Staff Writers: MacBook Pro 13 "Unibody Mid 2009 Reemplazo de vidrio de la pantalla frontal
The title of this article is unfortunately vague enough so that it attracts a lot of views from search engine results - even though it only applies just to the MacBook Pro 13-inch Unibody A1286 model - and not other models like the MacBook Pro Retina or (shudder) Touchbar. The actual iFixit staff-written guide is also limited to show under the replacement guides of the 2009 & 2010 variants of the A1286 MacBook Pro 13-inch Unibody even though the screen and front glass are constructed the same as each other for the subsequent years (2011 - 2012). Finally - this process is actually tricky enough to challenge experienced glaziers & repairers - so it needs a panel of writers & technicians to collaborate with a proper guide.
This guide needs to be replicated / linked on to all the other A1286 13-inch Unibody models as it was done with the 2010 model. The screens are the same for each year of the A1286 generation from 2009, 2010, early 2011, late 2011, and 2012.
Ideally, it could be really helpful if the staff team can improve the article; improve on the steps outlined; using the feedback received in the comments - e,g, safer ways to handle broken glass, use of solvents like alcohol or acetone to dissolve / neutralise the adhesive seal, and ways to preserve the rubber lining, the LCD panel itself, and the additional circuitry & cabling underneath.
Alcohol was the best bet for me - and I have a strip of class 2 HDPE plastic cut from a used chocolate milk bottle for the purpose of sliding underneath and “bridging” the alcohol underneath the battery and onto the adhesive. However, the actual adhesive tape bonding the battery to the case is far more resilient than the adhesive holding the plastic wrapping of the battery together - and, IMHO, only a little bit of it - less than a quarter of the original surface area - is required.
This phone definitely does not deserve a 7 repairability rating - and I kick myself that I bought it based on that rating. It deserves a “2” like its predecessor, the Nexus 6P… and I have firsthand experience trying to do battery replacements with the Pixel XL and the Nexus 6P.
I found that leaving the pick in the middle, and using it as a lever (think like bending a pipe over one’s knee and the pick in the middle is the knee) to “pop” the top edge up helped a lot more than trying to use more picks to pry this mid layer up…
From my experience, I had to use a thin blade (such as the ones included with the deluxe iFixit repair kit) to slide into the small gap, and cut away at the foam adhesive. Once enough of a gap is created, the picks can then be used to push the adhesive aside - but the adhesive is so thick, especially -as Brewmaster396 observed in the comments below - at the top right corner behind the screen, that the knife is required to cut it. I failed here - cracking the back layer of my screen - because I didn’t take time to cut all the adhesive away from that thick part, and kept trying to pull the screen off. It doesn’t take a lot of pressure to crack - so maybe it’s more a thing of cutting and floating the screen up, not pulling and prying.
From my experince, it’s better to use a heat gun (if iFixit sold a good heat gun in volume, they should spruik that). Also, heat ALL sides at the same time BUT concentrate on the top part of the phone where the foam adhesive tape is thickest, second on the bottom where the foam is almost as thick. It also helps to use the 2nd & 3rd images in the series to visualise where the adhesive is.