A1708 820-00840 won't turn on after battery replacement

[Sdogs]

this macbook had had liquid damage, i replaced trackpad connector, i also changed efi chip, battery was dead and put in a new one. Today I connected the battery without fixing with double sided tape, I switched it on and everything went smoothly. Before turning off I deactivated autoboot with a command from the terminal. I turned off, I unplugged the battery, I reconnected everything and now it does not turn on anymore. When I connect the charger it has a normal current draw and 20v, the symbol of the charged battery appears for a moment and then nothing, dead. It does the same thing if I close and reopen the lid, for a moment just the battery symbol.
What can I do? all this is very strange .....

 

[2informaticos]

Please, write in english; or use an online translator.

Test the board alone on the desk, without battery connected.
Do you get PPBUS_G3H and 3V3_G3H?

When you touch the battery, disconnect J6951.
Battery data cable is the first to disconnect and last to reconnect.

 

[Sdogs]

PPBUS_G3H 13v
3V3_G3H 3,4v

 

[2informaticos]

Test the board without battery connected.
Do you still get low battery symbol?

Check the voltage on the big coils; anything at L7210/20?

 

[Sdogs]

solved, I bought a bios chip already programmed, it worked for a day, I got one from another logic board and now everything works !!
I don't know if the terminal command "sudo nvram AutoBoot =% 00"
may have created some problem with the bios chip.

 

[2informaticos]

You need to clean ME region, or weird issues will appear on the future.

 

[Sdogs]

thanks for the information, I don't have a chip programmer, I would like to buy one, even for newer macbooks, which programmer do you suggest?
At the moment the macbook seems to be doing very well, very fast start-up, fans under control, perfect battery !!

 

[2informaticos]

If you plan to stay in business with Apple boards, buy Medusa programmer.

CMIzapper Medusa-3

You may need to get few EasyFlash adapters also; listed by models, like here:

MacBook Po Retina motherboards

You can use cheaper programmers, like CH341A; need to remove the SPI chip from the board, in such case.