Dell venue 11 7140 k12a shuts off the tablet (solution) soldering skill required

Hey Guys, this problem ist quite old (as the venue 11) but I finaly solved the shutting down with the Battery-Keyboard.

Problem: with the kb12a connected the tablet shuts down when the powercord is disconnected.

To make it short: Sho problem is inside the tablet, not the keyboard.

Solution1: Open the keyboard and disconnect the battery.

Solution2 (temporarely): I found out that there is a loose contact with the white ribbon cable inside the 7140 connecting the docking pcb and the main pcb. So open the 7140 and remove the battery. At first I removed the ribbon cable at the main pcb (lift the black part of the socket) and cut the ribbon cable for 1mm. This worked for one year, but then it was faulty again. At the ribbon cable the burning from the loose contact was even visible.

Solution3: I soldered at wire between the dock pcb and the main pcb. The wire should be placed just under the battery where the two lion cells. There should be enough space. But I had to cut the batteryholder a bit. See pictures.

OK, this is not a easy solution, and you will need good soldering skills and some courage. You can easily kill she tablet if you do something wrong, but this could give the great PC a second live with many hours of batterylive. 

Solution4 (perhaps): It could be a good try to replace the white ribbon cable if you can find it as replacement part. But i did not try this. I think in my case the contacts in the ribbon-cable-socket is damaged also.

Cheers /Hendrik/