Hey all. I've been getting bothered by my Pixel 5a to upgrade to Android 13 for a while now and am getting sick of it. I understand it's for security and bugs, but i know from experience that updates always cause phones to run slower, if not cause more problems with apps or features.
Actually I never had that experience with my Pixel 2 (originally Android 8, finally Android 11). Nor with my current Galaxy s21 (originally Android 11, currently Android 13). My previous phones always ran custom software anyway, so I never had much experience of official updates prior to this (I received the official update from 2.1 to 2.2 on my HTC Desire in 2010, which had no adverse impact, but rooted and moved to custom ROMs a fortnight later).
Does anybody know any options for full android image backups, or at least the next closest thing to that to restore the phone from a backup?
As Danny says, your best bet is to unlock the bootloader, flash a custom recovery (TWRP being the best known) and use that to take a system backup (often referred to as a "nandroid" backup). That will back up your Android 12 ROM, kernel, your current apps and their data. It won't back up your media etc, but you can back those up in other ways (including just copying over USB to a computer). Make sure you store the nandroid backup off the phone (in my rooting days I'd attach a USB flash drive and back up directly to that).
Unlocking the bootloader will factory reset the phone, so you will need to back up everything important before doing anything else.
Note that the nandroid backup can only be used to restore the phone back to the state it was in when the backup was taken. You cannot use it to restore apps or data to your phone without restoring the ROM as well (it would be a bad idea to try if you've updated the OS in the meanwhile!). So having separate backups of apps/data/media is going to be very important.
The nandroid won't back up everything: lower-level stuff like the radio firmware and bootloader are not included, but probably will be updated as part of the system update. It's likely that you'll have to reflash the stock recovery (replacing TWRP) before you can install an over the air update - it's been a few years since I did this stuff, but I'll be surprised if the over the air update will install if you have a custom recovery. XDA will know, and will have the tools and files you need if you have to.
The update will replace the recovery anyway, so if you want to restore to Android 12 then you'll need to reflash TWRP first.
With some phones there are tricks to allow you to manually flash an older set of official firmware over a newer one, but most don't allow this. You might want to research this for the 5a as well, since if that's possible it would provide another way of reverting that might involve fewer steps. Note that manual firmware flashes will usually reset the phone, and if you are reverting from 13 to 12 you would want to do that anyway, as it's likely that there will be system data with Android 13 that would be incompatible with Android 12 (and a reset is the only way to clear everything). Hence even if this is possible you'll still want to make sure you have backups of your stuff before reverting.
I realise that I'm making this sound very complicated, but it's better to be aware and to prepare properly rather than find you lose data because you didn't realise what would happen. You are asking for something the system isn't designed for, so it's not surprising if a bit of fiddling is involved.
