How to revive Prime from sudden death

[René Franquinet]

Recently I tried to update my Prime to the latest version 2016.04.14 r10077 . As I had to do other things I have left the Conmnectivity Kit alone to do the update without interfering. I noticed however a number of error messages. Of course I have no log of these. I have waited till the end of the process and tried to reboot the Prime. Impossible.
I did the following things to get my Prime alive again:
- push a needle in the reset hole: no result
- apply the magical key tricks as mentioned in several threads: no result
- remove the battery for a couple of hours and replace it: no result
- feeding the Prime with and without battery and the USB-cable connected to a power outlet: no result.
The Prime also is not recognized by the Connectivity Kit . Maybe I did forget the ultimate trick?