HP-15C LE bricked?

[Hans Brueggemann]

unfortunately, i don't have any pictures of the setup. to get a reliable electrical connection to the calculator, the 6-pin connector case for the back side was 3D-printed using TPU95A, a flexible material, which gives quite a good grip once inserted into the calculator. it needed quite an amount of trimming though to make it fit, hence no stl file for it, it's simply too ugly to be published.
contact pins for the connector are pogo-pins from digikey that i had on the shelf, don't remember the exact order code. the two buttons for RESET and ERASE were soldered onto a piece of prototyping pcb, and the whole contraption was then connected to the jlink with protyping cables fitted with dupont connectors.

i tried to investigate further on the voltage settings mentioned above, but couldn't replicate the behavior. hence, my conclusion on the difficulties i had with flashing the calculator is a wrong "timing" of pressing and releasing the buttons during the initialization sequence. maybe somebody else on the forum can give some hints on the timing that worked for him (her).