LGT8F328P - burn bootloader issue

I bought LGT8F328P LQFP32 MiniEVB, which is clone of arduino Nano. But it also uses clone of ATmega328P chip from Atmel -> LGT8F328P from LogicGreen. It have a lot of advantages (32 MHZ internal oscillator, additional 16bit timer, SWD, DAC, ...). Only disadvantage that I found is that it does not have "true" EEPROM (it uses FLASH memory to simulate EEPROM).

Suddenly, when I was playing with this fake EEPROM, the board stopped working -> I was not able to upload any sketch, and it also did not react to reset button. So I found out that bootloader is probably missing.

I have tried to burn bootloader with another arduino board (arduinoISP; burn bootloader - arduino as ISP) with out success (error: device signature 0x000000).
I have also tried to burin it with "LarduinoISP" sketch found on the Internet, but it is made for LGT8F328D (D not P). It uses arduinos SPI to simulate SWD interface (SWD/SWC/RESET). Again without success (error out of sync rc=-1).

Does anyone have any experience with burning bootloader on this board?
Could be the problem in fuses or baud rate?
I you have better luck than me could you post a link for any tutorial about bootloader on this board?
If is necessary programmer could you give a link for it?

Bootloader that should be burnt:

Datasheet: (3 translated versions)
(1) LGT8F328P-Testing/LGT8FX8P_databook_v1.0.5-English.pdf at master · SuperUserNameMan/LGT8F328P-Testing · GitHub
(2) https://www.avrfreaks.net/sites/default/files/forum_attachments/LGT8F88P%20LGT8F168P%20LGT8F328P%20translated.pdf

(3) find "LGT8FX8P_databook_v1.0.4.en.pdf" in this forum (I think tis is best one): other related resources · Issue #2 · RalphBacon/LGT8F328P-Arduino-Clone-Chip-ATMega328P · GitHub

Other discussion about this issue that could help:

Thank you for your helpful advidces.

So I found out that bootloader is probably missing.

Perhaps it is more broken than that. Do you know if "LarduinoISP"works on a known-good board?
AFAIK, none of the standard AVR programming tools (ArduinoISP) will work on the LGT chips.

westfw:
Perhaps it is more broken than that. Do you know if "LarduinoISP"works on a known-good board?
AFAIK, none of the standard AVR programming tools (ArduinoISP) will work on the LGT chips.

No, it is not working, because it is for LGT328=>D<= chip not …P. It probably uses different upload speed or have some other difference.

hi. did you succedes with the bootloder? i've locked my board and the upload does not work anymore. the program is still running but the upload fails. maybe because the loop() does never exit.

In April 2020 the LarduinoISP sketch was updated to also support the LGT8F328P

you can find it here: GitHub - LGTMCU/LarduinoISP: make arduino board to be LGT8FX8D/P programmer
Put all files in your sketchbook folder and it will compile.

In my boards.txt file I had to change the 328D-SSOP20 into the 328P-SSOP20

so this:
328.menu.variant.modelD_SSOP20=328D-SSOP20 (e.g. green pro mini alternative)
328.menu.variant.modelD_SSOP20.bootloader.path=lgt8fx8e
328.menu.variant.modelD_SSOP20.bootloader.file=lgt8fx8e/optiboot_lgt8f328d.hex
328.menu.variant.modelD_SSOP20.build.variant=lgt8fx8ds20

into this:
328.menu.variant.modelD_SSOP20=328P-SSOP20 (e.g. green pro mini alternative)
328.menu.variant.modelD_SSOP20.bootloader.path=lgt8fx8ps20
328.menu.variant.modelD_SSOP20.bootloader.file=lgt8fx8ps20/optiboot_lgt8f328ps20.hex
328.menu.variant.modelD_SSOP20.build.variant=lgt8fx8ps20

My boards.txt file is at this directory (Arduino portable install):
E:\Arduino\arduino-1.8.12\portable\packages\LGT8fx Boards\hardware\avr\1.0.5
so that may give you some help finding it.

With this I am now able to burn the bootloader on both versions of the LGT8F328 clones, but also can upload sketches to the board without having the startup delay of the bootloader, which is actually what I was looking for.
I just bought myself a SWDICE-MKII pro programmer off Taobao (via wegobuy.com) to get rid of the bootloaders, but that programmer is now redundant.

FYI I am using the LGT8F boards package from David Buezas: GitHub - dbuezas/lgt8fx: Board Package for Logic Green LGT8F328P LGT8F328D and LGT8F88D
Bootloader hex files are in his package.
I did not notice any difference with our without the 10K pull-up resistor.