This is a common problem on Lenovos, remedied temporarily by pushing in the charger plug.
Circled below is the problem area. The center pin of the plug is connected to the ring, the hard wire is connected to the board. The problem occurs when the connection between the two breaks. We will repair this with a solder joint. To do this repair you will need to remove the board from the machine, if you’re unsure how to do this refer to youtube disassembly videos.
Once the board is removed from the case you will have access to the top side as shown above. This is where we have enough access to solder a connection.
Flow solder between the two parts, as shown above.
This repair worked well.