Sorry to say, but I don't think there's any way to salvage the memories.
One of the reason why having a google/ any other cloud backup on is such a good idea and worth to pay for.
If you can turn it on in any way, it would be possible.
Also can't suggest you to go to any local phone shop as that might void your warranty.
Unsure but Apple stores via any contact if possible, try please, but I doubt even if he will have any control over the procedure.
While I acknowledge and even agree to the trial and error part, my approach to such issues was independent of the specific use case scenario or what goss8877 wants to retrieve.
For all i care, it could be messages detailing how to enrich uranium to make it weapons grade
OR
the script of what 'papa' says to get wars to temporarily halt.
Overall, if data is sandbox in an area (storage) which is not corrupted or damaged, then (at-least theoretically) whatever is encrypted can be decrypted too.
And yes, we do not enforce laws like EU does and we do not force businesses as much as EU does by changing or bringing new laws.. so here, getting such data recovery help 'might' void warranty.
But depending on the level of third party repair, I feel that in some countries it might be a grey area if right to repair laws are a bit fluid.
Apple warranty is giving a replacement and if it is with an unused and new/seal piece then it might be a good deal (although it is ridiculously dampening to loose data permanently.)
Agree, whatever encrypted can be decrypted. But there is also something called value addition. Most repair experts can fix if it's a component level repair/replacement. If it comes to decryption via external provisions, it falls under highly advanced category. While hackers may be able to do, it's Apple if at all who can build the decryption key. And all this involves massive time and efforts. I'm not discouraging but it isn't worth IMO.
Most of the times it is going to be a burnt power management IC or some passive components or a weak pcb track. But we never know until it's opened.
I recently brought a Lenovo yoga pad to its glorious life with a simple decoupling capacitor (2mmx3mm size)replacement. But it took me efforts/time to fix it.
But I see no reason why... How you can be sure that your data on the storage chip is inaccessible. Your phone isn't turning on could be due to plethora of reasons. From common short , to faulty SMD components, even a a dead battery.
So my advice is find a good 3rd party repair Shop who has the necessary skills and necessary equipment ( like microscope to work on tiny electronic chip level SMD components repair, and oscilloscope for electronics diagnosis. Prefer ones who has experience repairing the exact model of iPhone as yours before. Most of these shops in these days have also invest in a good thermal camera to easily and quickly find shorts on any PCB
There's no quick and easy way to determine how good a electronics repair shop is. But All of the professional repair with highly trained repair technicians should have those equipments.
And ask them to be careful not to mess with the motherboard trying to figure out the problem, as your priority is your data more than fixing your phone's hardware.
If everything fails. You might need to send your phone to reputed repair/ data recovery service abroad in USA or or Europe.