iPhone keeps randomly turning off

Hello everyone, I find myself in a rather challenging situation with my iPhone 13 mini. Ever since I updated to iOS 17, my iPhone has been shutting down randomly and refuses to turn back on, regardless of what I try. I've attempted the volume up, volume down, and hold power button technique (trust me, I've repeated this process more times and for longer durations than you can imagine). The only solution I've found so far is to take my seemingly lifeless phone to an Apple store, where they perform a forced reboot. I've had to make this trip a total of three times because I'm a student and can't afford to purchase a new phone outright. This suggestion came from an Apple Genius technician since I originally bought my phone in the US, and it couldn't be repaired in the UK.

Each time I visited the Apple store, they ran a diagnostic test, and each time, everything appeared to be in good health. My battery and hardware checked out fine, and the only explanation the Apple Genius technicians provided was that it's a "glitch." Living this way is not an option for me, as I rely on my phone for both school and work, and I'm currently unable to afford a replacement. I almost got fined in the London subway as my phone had died during a trip and I didn't have a way to prove that I had bought a ticket at the exit. I'm feeling frustrated and like I've been taken advantage of by Apple, the Genius technicians aren't providing me with any sort of useful help or information and I've exhausted all available solutions. I'm strongly convinced that this problem is a result of iOS 17, something that is completely out of my control. What options do I have?

Thanks.

[Re-Titled by Moderator]