On Mon, 02 Oct 2017 08:50:00 +0200
"Marius Schrecker" <marius.schrecker@lyse.net> wrote:

> CH341a programmer -> 1.8V adapter -> test clip with original ribbon cable clipped to one of the new chips.
>
>   The flash procedure worked and verified flawlessly, so there is either some interference from trying to flash the chip on board, or the original chip is damaged.

If by original ribbon cable you mean the one with a length of some dozen
centimeters... then you have broken the first rule of the flash club:
short cables!

--
Kind regards/Mit freundlichen Grüßen, Stefan Tauner