iPhone 3GS Can't Be Detected

[michael29angelo]

My iPhone 3GS 6.1.6 can't be detected by iTunes, computer, and other softwares.

• I've already tried using another USB and another computer but it didn't work.

• The screen of my phone is completely black.

• Whenever I try entering DFU or recovery mode, it won't work.

• I tried charging the phone but nothing appears on the screen.

What should I do? It is a second-hand phone and before these events happened, I've jailbroken this phone unsuccessfully. Please, help!

 

[Applejuiced]

Sounds like it has a hardware issue.
Maybe the bottom usb dock on the phone is faulty.
See if it has any dirt, dust, lint or anything down there. If its scratched, bent pins etc....