I used Neoprogramer 2.2.0.10. and CH341 flasher I2C protocol socket. Just 2 days ago I ordered SOP8 DIP8 connectors and 1,8V adapter, hoping that I would flash the BIOS chip of this laptop, thinking that the BIOS chip is 1,8V supplied. According to boardview the BIOS chip was supplied with 3,3 V, I also measured with multimeter right on the motherboard and the supply voltage was 3,3V, datasheet says supply voltage 1,8 - 5,5V. The same is with the U15 chip, I checked datasheet and range is 1,8 - 5,5V. On boardview the supply voltage for PD controller memory is 3,3 Volts. Neoprogrammer recognized...

Fantastic. Happy to read that. Did you flash the bin provided or you repair it other way?

Here is the firmware for PD controller U15 CAT24C256WI-GT3_SO8. Extracted with Neoprogramer 2.2.0.10 from laptop:
BIOS: Giga device, GD25R256EYIGR
Lenovo Thinkbook 15 G4 IAP
S/N: MP2EK6MY
MTM: 21DJ009RCK
MO: MPNXB330709A
Motherboard: HLXA4 LA-L931P Rev:1A
Hope I did it right.
Hope it helps....

Tomorrow, I will try to grab the laptop and get the bin for you. I have exactly the same model and the charging is all right.

I flashed bios 4 times. Disaabled onboard ram with app removal, then disabled ram with pull down resistors. Always ended up with same symptoms, laptop on but no picture, capslock dead and esc light on, charging fine turn on fine. Then i realised that checking the coil resistance would be a good idea. All coils were good except RAM coil. Although I had 1,2 volts on it but the resistance was 10 ohms. So I injected 1,2 on that coil but nothing was warming up and current that drew was 0,9 amps. Then I disoldered onboard ram but resistance on the coil was still 10 ohm. Later on the resistance dropped...

Thanks a lot for the bios. I flashed it with no success. Also used SPD removal tool. Still not working. I had 10 ohms on RAM coil. Removed all onboard chips. Now I have 1,2 ohms on the coil. Laptop starts for few seconds. On RAM coli I have 1,2 volts. All voltages present.

Thank you for reply.
Display is good, LVDS good, all connectors checked....
The board is not ON, CAPS lock is dead and ESC ligt is on....
Laptop is restarting in almost periodical manner...
I went on with disabling SPD on original bnios and end up with only 1 fan spin by the first power button push.
Second push is 3 x fan spin and off......
Thank you for suggestions...
I think...it looks like corupted bios....
Can I prosede with bios from different laptop...
I do not care about serial number.
Thanks a lot for reply....

Hello guys. Seeking for your help. My frends son dropped lenovo thinkbook 15 G4 from bed. Laptop stopped working. Turns on with no picture. Lights on, fan on, charging fine. All voltages present. Although charging coil and driver is bloody hot, going crazy hot is also area around onboard ram, strange.. Tried reflow onboard RAM. RAM has glew. Didnt help. Have none experience with these new laptops. Can I flash any bios on it or must be original from factory, because of the S/N or others? Should I disable onboard RAM? Could be damaged or I damaged it with reflowing. Dont have original flasher socket...