My iPhone won’t work because of Apple Update! Please help!

Okay. This all started on the day I got my drone (Christmas Day). The drone was a Mavic Mini Manufactured by DJI. I used my iPhone 7 Plus to fly it which I got for Christmas last year. On June Apple unveiled IOS 13 for iPads and iPhones. A few weeks later the public beta got released which I was very eager to download because of all the new cool Features with it. So I downloaded the public beta profile from a website that had the betas. The profile was verified and had a genuine Apple certificate on it. Then I updated to the IOS 13 beta versions until the final release comes out. The beta versions worked perfectly on my iPhone 7 Plus. When the final release came out I forgot to update to the final version and delete the beta profile. The beta version and profile remained on my iPhone 7 Plus until today, when a couple of days ago I noticed strange behaviour on my phone. Some apps would keep crashing causing me to restart my iPhone, and that would happen very often. I also noticed that sometimes when I restarted my iPhone using the hard reset method a setup screen will come up when it comes back on telling me that an update has been complete and telling me to enter my Apple ID and password. On the day I was going to fly my drone at night, I noticed the app used to fly the drone (DJI Fly) kept crashing. After the first crash I noticed some apps on my home screen were invisible but still able to open. The app used to fly my drone on the home screen was then replaced by pixels which didn’t go away unless I restarted my Phone. So I hard resetted my iPhone by holding the volume, power and home button(s) and it resetted. It then displayed the setup screen again telling me that an update which there wasn’t and it told me to enter in my Apple ID and password. After I entered the details a screen came up saying unable to activate iPhone because the activation servers are down. So I restarted my iPhone for it to be stuck on the Apple logo forever. I kept restarting it and one time it showed me the setup screen again with the activation error. And then it would go back to the Apple logo when I restarted it. We attempted to do an update via iTunes of the system by connecting in to iTunes and putting the iPhone into DFU Mode. The dialog on the iPhone for connection to iTunes came up and iTunes could recognise my iPhone. While we attempted to update my iPhone the dialog box saying “An update to this iPhone is being delivered. Please wait” Stayed there on the screen and my iPhone stayed on the DFU Screen. We left it like that overnight but nothing happened. We then tried to format it but nothing would still happen. So after a whole load of tries taking the sim out, restarting the iPhone, Updating the iPhone we gave up and decided to hand it over to an Phone repair shop in Town. The store was Phone Clinic. We left them to try to fix it but two days later the store called saying that it cannot be fixable and is permanently broken and we would have to come pick it up. Once we picked it up, my mum took it to a local Apple store in this case the store was called Stormfront which was like the Apple store but more of a tech info centre. I am at home while my mum takes it to Stormfront and I am very worried that it would have been broken permanently and Apple destroyed it! Now I am stuck with an old slow iPhone 6 that my dad used to have while the other phone gets fixed. How can my phone be fixed? This is a Nightmare!