I've been following this long thread for years, and want to thank Karl-Heinz, the two Markus, indman, and the whole crew.
I have had a dozen of these component testers (haven't burn any, knock on wood), and I currently have a a T4, a TC1 (wondering how a recent m-firmware would look running on it), and other one I don't recall anyone reviewing it here, so here I go:
The PCB states WEI_M8_shell_TST. It has a 3.7V battery with a physical switch, a Mega328p, an 8MHz crystal, several scratched ICs, and 3 nice test leads plus a ZIF socket with extra PCB options, a monochrome graphics (don't know the controller). The 1.11k firmware was modified by VANVELL ELC.
I have used it for testing quite a lot of components without problems, and I'm happy with it. Nevertheless, I wonder whether somebody already updated the (k or m) firmware for it, although I've not studied how to connect the programming interface yet. Shall somebody already acmomplished this, please point me to the right place. (I could also remove/replace the 431 and try to switch to a 16MHz crystal, but first thing first).
I attach some pictures.