Then I tried to flash an older firmware with TL866.exe (version 2.52). I soldered a resistor from +3.3V to register R26 as described in the documentation.
Then I tried to flash the firmware dumper and the TL866.exe showed that it was first erasing and than writing something. Than I got a "reflash failed" message. I tried several times. Always the same result.
Now the device completely dead. It is no longer recognized as USB device.
kalle
That reflash failed message was caused by that resistor. Until you remove it the programmer will keep enter into boot mode after power up or reset. My firmware updater will test the reflash success status by looking at the device status after the reset command. If the device status is ''Normal mode" then a reflash ok is issued, otherwise if the device is still in boot mode you'll see that 'reflash failed' message. So that resistor will force to always start in bootloader mode even after a succesfull firmware reflash.
So the problem here is that you can keep reflash your device and you will get that annoying error message until you remove that resistor. But this will not brick your device. Something else happened here.
Restoring a bricked device is easy, but you will need a PIC programmer. The most simple one is described at the end of that pdf file. three resistors an a DB-25 male connector. Of course you will need a quite old computer with a real LPT connector on the motherboard.
If you can't find one, maybe you can borrow a Pickit from someone. Also check this:
http://picpgm.picprojects.net/hardware.html The PicPgm software accepts a plenty of hardware programmers. Maybe you have an usb to serial adapter (PL2303 or FTDI based) to make a JDM programmer like this:
https://www.instructables.com/id/The-2-USB-Pic-Programmer-Serial-CableAnyway generate a new firmware with my firmware updater tool and if you encounter any difficulties please reply here.
I checked autoelectric’s website and it looks like a new programmer is going to launch soon. If I read it correctly it will support Vpp > 18V!
http://forums.xgecu.com/redirect.php?tid=19&goto=lastpost#lastpost
I think I may hold out until it launches...curious if anyone else knows any more about it?
I found the first reference of the Xgecu T56 while searching for some strings in their software back in january 2018 or so and i was quite confused because i saw that the Xgecu software has some implementations for another programmer (other than TL866II+) so yes is about two years since then and is still in the development stage.
Specs are OK. 32bit processor, 56 pins and other cool stuff. Unfortunately same Windows closed source software no other OS support and maybe easy to brick as their first two programmers. Because i'm also involved in the open source software for their TL866A/CS and TL866II+ programmers i know how difficult is to keep the open source software up to date with those firmware changes introduced in each software version. So i doubt about any collaboration with them to release some docs about the protocol or something else, because what we have right now is based only on reverse engineering.
The only strong point about their programmers is price.