Quattro B6AC Invalid device signature.

[giubu]

Hello to everybody and first of all, let me say I am deeply grateful to everybody involved in this project.

Somebody gave me this charger because it didn't work.
After fixing the hardware side of things I am now taking care of the FW upgrade.
I have successfully installed cheali-charger-imaxB6-clone_2.00-e10.3.12-20160613_atmega32.hex on 3 of the four chargers.
The fourth one is giving me trouble. I am using a NANO as ISP programmer. I have to solder on the traces next to the ATMEGA32L as there are no headers available.
This fourth MCU is not recognized.
`boombox@BoomBox:~
$ sudo avrdude -p atmega32 -c stk500v1 -P /dev/ttyUSB0 -b 19200 -U flash:w:"cheali-charger-imaxB6-clone_2.00-e10.3.12-20160613_atmega32.hex":i -F

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
avrdude: Expected signature for ATmega32 is 1E 95 02
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "cheali-charger-imaxB6-clone_2.00-e10.3.12-20160613_atmega32.hex"
avrdude: writing flash (31738 bytes):

Writing | ################################################## | 100% 35.34s

avrdude: 31738 bytes of flash written
avrdude: verifying flash memory against cheali-charger-imaxB6-clone_2.00-e10.3.12-20160613_atmega32.hex:
avrdude: load data flash data from input file cheali-charger-imaxB6-clone_2.00-e10.3.12-20160613_atmega32.hex:
avrdude: input file cheali-charger-imaxB6-clone_2.00-e10.3.12-20160613_atmega32.hex contains 31738 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 19.63s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
0x00 != 0x0c
avrdude: verification error; content mismatch

avrdude: safemode: Fuses OK (E:FF, H:00, L:00)

avrdude done. Thank you.
`
The strange thing is that, after unsuccessfully trying to write to it, when I power the unit on, this charger LED shows black squares on the top row.
Before, it was working normally, showing the Skymax B6 welcome screen.
Any help is greatly appreciated.

by the way, on a side note, when calibrating one of the chargers, in the Idischarge high current process, the initial calibration value was so off that i pulled more than 8A and the discharge mosfet and resistor blew. It might be an idea to set the initial calibration value very low, and let the user increase it as needed.