1. Check Device Power On

1.1. Connect the AC adapter to the NLBA1 device
1.2. Check if the Power LED is ON
1.3. If the Power LED is OFF then check the AC adapter output voltage
1.4. The AC Adapter output voltage should be 19-20V DC

2. Check USB Connection

2.1. Make sure the Prolific PL2303 driver is installed. The driver is installed automatically with NLBA1 software. During NLBA1 reinstallation, the PL2303 drivers asks for Removing, do not press Yes, otherwise the PL2303 driver will be removed.
2.2. Make sure the USB cable is connected to the PC after connecting the DC Power Supply first to the NLBA1 device.
2.3. If the NLBA1 device is not discovered by the software in the drop-down list then the U1 chip Prolific PL2303TA could be damaged and has to be replaced. Make sure the replacement part is original, otherwise, it will not work.

3. Check Server Connection

3.1. Make sure the following startup sequence is performed in the correct order:

3.1.1. Disconnect the DC power supply (jack connector), the USB cable and the battery from the NLBA1 device
3.1.2. Close the software
3.1.3. Connect only the DC power supply (jack connector) to the NLBA1 device
3.1.4. Connect the USB cable
3.1.5. Run the software and press the Connect button. The software should successfully connect (Disconnect button is shown)

3.2. If the Connect button switches to Connecting (yellow), stays a few seconds then switches back to Connect (green) then check the following steps:

3.2.1. Disconnect everything from the NLBA1 device. Open the device enclosure (only if you agreed on this with the seller or if the device is out of warranty)
3.2.2. Measure the voltage between G and V on the 6p Programming Connector located on the PCB. The measured value should be approx. 3.55V, tolerance +-0.1V. If the voltage is much lower then check the next step.
3.2.3. On the 6P Programming Connector, measure the resistance between G and V. If there is a short between G and V then the U5 chip is damaged and needs to be replaced. In this situation, U2 chip LM317 gets hot because it runs in over-current protection mode. The U5 chip is flashed with firmware and it is secured. A new blank U5 chip will not work, only the chip shipped by the manufacturer (already flashed with the firmware) will work.

4. Check Voltage Generator

4.1. Connect the DC Power Supply to the NLBA1 device, connect the USB cable and start the software. Remove the battery if any is present.
4.2. In the Software, go to the Device Control -> Output Voltage Control section and set Output Voltage = 10 000mV then press Enable.
4.3. Check if the Output LED is ON and measure the voltage on the Battery Connector between G and V. The measured value should be around 10 V, accepted tolerance of +-0.5V.
4.4. If a wrong value is measured then open the device and check physically the U3 chip XL4005. If it is physically damaged/blown/burned then the chip has to be replaced.
A new one can be ordered from eBay or Aliexpress.

5. Check Communication with the Battery

5.1. If you are 100% sure that the battery is good/working and wiring is done correctly but still no reading then check the following steps:

5.1.1. Remove the battery from the NLBA1 device if any is present
5.1.2. Re-connect the DC Power Supply to the device and the USB cable
5.1.3. On the Battery Connector, measure the voltage between G and C, it should be 2.6-2.7V
5.1.4. On the Battery Connector, measure the voltage between G and D, it should be 2.6-2.7V
5.1.5. Disconnect: the DC Power Supply from the device, USB cable and battery
5.1.6. On the Battery Connector, measure the resistance between G and C, it should be 2.6-2.7 Kohm
5.1.7. On the Battery Connector, measure the resistance between G and D, it should be 2.6-2.7Kohm
5.1.8. There are 2 Zener diodes, one connected to the clock line (D7) and one connected to the data line (D6).
5.1.9. Check the D7 diode: set the multimeter to diode mode, and connect the red probe to G and the black probe to C. The measured value should be ~0.6V
5.1.10. Check the D6 diode: set the multimeter to diode mode, connect the red probe to G and the black probe to D. The measured value should be ~0.6V

If one of the above tests (voltage test, resistance test or diode test) fails, remove the diode from the corresponding failed line and try again to read the battery.
Pay attention, after removing the diode, the chip U5 is not protected anymore, make sure you connect the battery 100% correctly.

If reading is working after removing the diode then the diode is damaged and has to be replaced:
D6 and D7 diode specs: Zener, 3.6V, 0.5W, Minielf package.

If Battery Reading still does not work after removing the damaged diode then the U5 is damaged too and has to be ordered.