iPhone recovery mode and DFU mode does not work.

Recently, while i was using my iPhone, it suddenly restarted and turned off. I restarted it again to turn it on, and it was stuck on the apple logo. I restarted it again, and it still was stuck on the apple logo. Eventually, it went into recovery mode by itself. I did the whole process of recovery mode and it did not work. I downloaded the software update required for recovery mode, 3 times, and all of those 3 times it did not work, saying that there was an error. I had to restore (which basically means it deletes all your data and content) and that also did not work, saying that my iPhone had to be restored first for it to be restored. I came down to my last option, which was DFU mode. It also did not work. The software update downloaded and my iPhone displayed the loading bar that appears when updating iOS software, but it had no progress loading for more than an hour. I was using iTunes for it, and on iTunes it stated "waiting for update verification" at the top centre, and then eventually, after almost 3 hours, it said "iPhone has to be restored before it can be restored" just like the DFU error.

Prior to this event, my iPhone was beginning to act up, it started late November 2017. It would constantly crash out of apps, apple apps, games, etc. It would also not screenshot correctly either, only screenshooting half of the screen. I would have to constantly restart my iPhone just to use the phone app to calI, or to use any other app.

I thought maybe if i updated my iOS software, it would be fixed.

The first time recovery mode happened, I was updating my iPhone to the newest iOS software and it went into recovery mode, i was able to recover it. (More problems started to occur within my iPhone, like the paragraph above)

After apple released more iOS software updates, (about 2 updates i believe) my phone would always go into recovery mode while updating. The third and most recent time, i had to restore my iPhone, but luckily i had an iCloud backup.
If another iOS software update was released, i would probably not update my iPhone, just because recovery mode is very time consuming and i don't want to risk losing all of my data again.

Does anyone know what is wrong with my iPhone? I've tried every solution, from restarting my iPhone, deleting the apps that were crashing, etc. My phone is not a year old yet, it is an iPhone 7 plus. My brother has an iPhone 6 and his phone had no problems like mine did, he was on the same iOS software. I read that another user also had a similar situation like my iPhone, and she had a hardware issue, i assume that my iPhone does too. I also may be getting a new phone soon, too, and i am confused on the Find My iPhone part because i cannot access my phone.

TLDR: iPhone acted up, phone restarted, tried recovery mode and DFU mode multiple times, stating an error: this iPhone has to be restored to restore it first. Getting a new phone soon, i don't know what to do with the Find my iPhone. Anyone know a solution where i can fix my iPhone and get access into it?

Thank you!