Yeah, iphone parts are very rarely interchangable, even with other iphones! There will always be either a piece that wont physically fit (like a connector) or even if it LOOK S like it fits, if the resolution of both cameras isnt exactly the same it wont work. The hardware still needs software to work, and the software is designed to work only with the hardware it came with. you used to be able to 'Frankenstein ' some older phones but they were not too reliable and it almost never worked with anything made by Apple, they want you to send your device in so they can fix it & charge a bundle. Replacing camera is easy, but make sure you get one for the EXACT model of iphone you have.

If you have a windows disk or stick, you can reinstall the OS which Im sure you know, but sometimes even that doesnt work when you've had this kind of issue. Trying to repartition & format the drive just keeps failing. Windows has issues with recognising and formatting drives, so I dont use Windows for that, i use Linux. You need to wipe the filesystem and start over, Windows will only recognise NTFS filesystem & a few others, but it needs to be installed on NTFS. I'd test the HDD to make sure its not failing, best way is with a linux live CD or usb, something like Ubuntu or Mint is easy to use and free to download. Usually there is a program on there called gparted that is ideal for changing partitions etc. Then wipe the HDD completely using the same disk or USB. You will need to format your HDD as NTFS for windows, but as long as you delete the partitions using the live CD, when you go to install windows again it should format the HDD as NTFS and install with no problems. i should mention that if you...

Sure, I have repurposed old phones and a tablet into a bluetooth video doorbell system using a bluetooth chat app, I see no reason why you couldn’t.

you could check your network settings and make sure you aren't set to 2G or 3G only assuming your SIM is a 4G or LTE type. Usually it's set to auto-detect or fall back if one network is having problems, but it's something easy to try. I'd reboot afterwards if you end up changing it. There are also a few apps on the Play store that will read a SIM and give you diagnostic info, probably won't help you but the info may help your carrier fix the issue.

Not really…ADB is what most people use for android but it’s not as user friendly. If you check around on XDA website there is quite alot of software there; (ADB included) but it’s not all neatly packed into one program unfortunately. If you are looking to flash firmware on a Samsung you would typically use Odin if you’re running Windows.

This may seem odd, but did you replace ALL the screws you took out with the originals? I haven’t taken apart an iphone in awhile, but I remember some older models wouldn’t work properly unless they were ALL put back. Sometimes people leave a few out to save time when they test that it’s working, and of course it won’t.

It is possible, but unless you have some experience soldering tiny wires, you may do more damage than good. Lots of shops replace charge ports for alot less than the cost of your phone. If you still want to DIY I’d practice on something else first. You’ll need some tools, so the cost may be no less than just going to a shop unless you already have everything. As for parts, I usually just buy on Amazon or eBay, but a google search will find plenty of sellers, depending on where you live. partsforrepair.com is a good site for parts too.