Please have a look at this (not very encouraging) threads. Maybe it is just the cable … but it sounds like the connector on the board of the phone is broken. You need to find someone who can solder it onto the main board for you with the right tools.
Maybe you can find someone in your area for this. Sometimes young people setup “fix shops” or “hacker spaces” that have these kind of tools. Else you need to buy a new main board … or a new or used phone
