After market install 01 ford escort zx2?

I have an 01 ford escort zx2 that has an after market stereo system. This vehicle is fairly new to me but for some reason the stereo doesn't have power. I have checked fuses and all the normal things. Upon further research I have found that the ground wire is not connected and I'm not sure if it can be soldered or if it needs to be replaced completely. Any insight would be very helpful.After market install 01 ford escort zx2

Just connect your after-market head unit's ground wire directly to that broken-off black wire, bypassing the plug.

Plug it back in to that discolored hole. That's probably where it goes. Black wires are usually ground. Make sure the connection is clean. If smoke comes out anywhere sell the car.