Check what is the monitoring chip installed on the pcb. 

@tracker135n9 

I need short approval from user before teardown the batt. But here is the preliminary check : 2S 4cell, 2 of 4 dead . both 0 voltage. The other 2 drop to  1.2v and 0.9v but it can still be charged to 3.2v.  I think these aren't very good either.

The biggest challenge here is that it’s quite difficult to find a lipo pouch battery with the exact same dimensions and capacity as the unit’s original battery so that it will fit inside the machine.

I really want to power on the chip, so I can view the data and copy the hex file for future use

any suggestions?

@mediriffat 

Paste a picture with the other side of the PCB.

@loliconic 

 chip number 732020. fuse ok

 Clock and Data already marked on the pcb. So double check the wiring. Also note that for some chips 6v is not enough for wake up. 

Posted by: @mediriffat

The other 2 drop to  1.2v and 0.9v but it can still be charged to 3.2v.

 Yes. Precharge these cells above 3.2v. 

 Instead of zero-volts cells install temporary any other cell, for example 18650. Balance it to same voltage like another cell. 

 Then wake-up the chip and try to read the battery parameters. 

@tracker135n9 

interesting. As far as I know, even without a battery, bms can still connect to the app. Could it be that the SMBus connection isn’t working properly ( I'm pretty sure the pinout is right ).  or is there something wrong with this IC that’s preventing it from being detected ? according datasheet the chip is MAX17320G20 from Maxim-now Analog Device

in paralel I will do what you suggest, to temporary attach 2 cell replacement. I will inform you the result later

Posted by: @mediriffat

Could it be that the SMBus connection isn’t working properly

 Yes. Confirm there is 3.3v on the SCL, SDA lines on the battery side when it is plugged to the device. 

Posted by: @mediriffat

or is there something wrong with this IC that’s preventing it from being detected ?

Yes. In this case diagnostic should be carried out in the lab. To understand what is wrong. 

Posted by: @mediriffat

according datasheet the chip is MAX17320G20 from Maxim-now Analog Device

Yes, correct. Datasheet says it supports SBS so it could be read by NLBA1 on the BatInfo page. 

But take note that max17320 is not supported by the license so neither firmware nor eeprom could not be read from it. 

@tracker135n9 

yes there is 2.6v on the SCL, SDA lines . instal 2pc of 18650 as replacement  with 3.7v each, test still no connection.

I re-check SDA and SCL with multimeter, SCL 0.8  but the SDA show 3.4 ?

I was so curious that I compared the two lines using Huntron Tracker, yes there's difference. SDA line seems problem, looks like either the zener diode or the IC input is faulty, or both   

Posted by: @mediriffat

I re-check SDA and SCL with multimeter, SCL 0.8  but the SDA show 3.4 ?

 Could you confirm that this check was done in diode check mode with NLBA1 disconnected from the battery ? 

yes, sure. 

btw I will put this job on hold while I wait for an update from the customer. Apparently, they will be sending another battery that is also failing to charge.

thanks