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I found my brother’s old iPhone 5s and I put it on the charger and the screen didn’t turn on. I tried to “restore and update” it on iTunes and it always gets to The point where the apple logo shows up as well As a progress bar and than “a unknown error occurred (40)” shows up.
Hi From what I know iTunes error 40 is a issue related to ether the iPhone or the computer through a hardware issue Have you tried the following : Make sure iTunes is up to date Reinstalling iTunes Using recovery mode on the iPhone If it were the iPhone I wouldn’t suspect it to be the NAND (NAND rarely fails without reason)but it could be battery related due to the phones age,old battery’s can cause all sorts of booting issues so if the above doesn’t work possibly give it a shot If you decide to do the replacement here’s the guide you will need How to replace the battery in your iPhone 5s Hopefully this helps Any questions please ask Thanks:-)
