Hi Sam,
Fellow Pixel owner here (6 Pro). Given you've already broken two rear covers, I'd suggest not messing with its attachment to the frame, but rather just bite the bullet and go ahead with the recommended rear cover replacement procedure. I don't see one on iFixit, but the Spanish site Nadie Me Llama Gallina (Nobody Calls Me Chicken) has exactly what you need to do the job.
Manuales / Google Pixel 7 Pro / Carcasa trasera con componentes - Nadie Me Llama Gallina
The site supposedly has an English language option, but it looks like it only translates the titles and not the text in each step of the procedure, so you'll need to use Chrome's translation feature with it if you don't speak Spanish. Otherwise it's a well done guide and will get you through the process with little pain.
Best of luck and let us know how it all turns out!
@sam78861 This is a fairly complex repair and of course there's always a chance something could go wrong.
That being said, I'd say yes, follow the guide carefully. The places I got into trouble when I was starting out were in getting the FPC connectors plugged in without damaging them; the secret here is to put your finger on it and press down lightly until you feel it drop into its proper location, then press it into the connector until it clicks. You should never have to push hard to get one plugged in.
Another place to watch out for is in removing the screen. Work carefully and use plenty of heat; I wouldn't recommend a heat gun, as I've gotten a screen too hot with one and ended up ruining it, but a hair dryer and/or an iOpener will do the job just fine. If you feel resistance, heat it up some more, working around the edges until it's open. Use several guitar/opening.picks to keep it from sticking back down as you work.
Finally, a screw mat is invaluable and a must have for any Apple product, but it's a little less of a requirement for an Android phone as they tend not to use as many different screws. That being said, pay attention to where the screws came from and do your best to get them back where they came from.
When putting it back together, clean the screen off well with Q-Tips and 90% or higher concentration isopropyl (rubbing) alcohol; don't get carried away, as it can cause problems if you get it into the display itself - it's usually okay after it dries, but if you're somewhat frugal with it, it won't be a problem in the first place.
Finally, grab. couple of sheets of precut adhesive for the screen. The thing is, it's not forgiving whatsoever, so if you don't get it on right the first time, you don't get a second chance at it; instead you'll end up with a tangled ball of glue, so having a spare on hand will keep you from having to wait to reorder before you can put the phone back together. Yes, I speak from experience, lol.
When gluing screens down, I usually secure it in place then heat it up like I did to open it, but then either clamp it, put some rubber bands around it, or set some weight on it and leave it for a while; I tend to try and wait at least a half hour, but if it's not a hurry I like to let it sit overnight.
When unplugging the FPC connectors, use a plastic tool; you're a lot less likely to damage something else with a plastic spudger vs. something made of metal. Use care that you don't damage any surface mount components that are mounted to the board right next to the connector you're unplugging.
Likewise when you get the the tiny little coax connectors, use tweezers to grasp the connector by the metal part; don't try to remove it by holding it by the cable itself. Like the FPC connectors, use care when plugging it back in; use the same strategy of pressing lightly with a finger until you feel it slip in place before pressing it down.
When removing the battery again, don't use metal tools; a plastic card is good, but a plastic spatula will do the job. Using syringe to squirt some isopropyl alcohol under the battery will help loosen the glue and make it easier to remove; if it's really stubborn heat the rear of the case as well; never heat the battery itself. Be careful not to deform or damage the battery in any way; if you do the best thing would be to replace it rather than risk using a battery that's been bent, scratched or dented. Of course, should you accidentally tear the outer cover, you must then replace it.
Well, hopefully I've covered most of the learning experiences (i.e., major screw-ups) I've made and with any luck that'll help you avoid gaining your experience the same way I did.
Good judgement comes from experience.
Experience comes from bad judgement.
As you've noted, this is a rather complex repair and perhas not one I'd recommend for a first phone repair, so while I would encourage you to go for it, if you're not confident in your ability to get through it, there's no shame in calling in the experts and taking your phone and replacement part into a shop to have them do the job for you.
Good luck; take it slow, follow the directions and be sure to ask for help if you get stuck!
I'll be looking forward to hearing how it all turns out for you!
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