I had the same problem with an iPhone SE 2020 where the battery went dead.
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I had the same problem with an iPhone SE 2020 where after replacing the battery, iPhone was still at a black screen with no signs of life. (No vibrtions or response to trying a hard reset)
Solution:
1.) Replaced the battery (screen was still black after battery replacement).
2.) Plugged it into computer. (Computer said iPhone was in DFU Mode would you like to download and restore?)
3.) Clicked on “download and restore”
4.) Waited 20 min and the iPhone was up and running!
I had the same problem with an iPhone SE 2020 where the battery went dead.
Solution:
1.) Replaced the battery (screen was still black after battery replacement).
2.) Plugged it into computer. (Computer said iPhone was in DFU Mode would you like to download and restore?)
3.) Clicked on “download and restore”
4.) Waited 20 min and the iPhone was up and running!